While filming a fight scene with Milla Jovovich, a mishap occurred causing 16 actors to fall off a scaffolding and sent to the hospital. As a result, filming was shutdown for a few days and Jovovich visited some of the actors in the hospital out of respect.

The scene between Ada Wong and Alice in the underground office is a re-enactment of the scene in Resident Evil 4 (2005) where Leon S. Kennedy meets with Ada for the first time in the Salazar Family castle bedroom. Wong wears the exact same outfit in both the game and this movie. The film also includes Ada's climbing pistol and her interactive sunglasses from that game.

The voice over narrator for the film's teaser trailer in the form of a fictional Umbrella ad 'This Is My World' is Patrick Stewart.

Bingbing Li's entire dialogue was dubbed by Sally Cahill who voiced Ada Wong in the video games (Resident Evil 2 (1998), Resident Evil: The Darkside Chronicles (2009) and Resident Evil 4 (2005)).

During the car chase with the Zombie Russian army the music playing is called 'Phantom Chase' by tomandandy. This references music from the original Resident Evil (1996) video game, particularly 'Second Floor Mansion'.

Las Plagas is a parasite in the video games (first seen in Resident Evil 4 (2005)) that takes behavioral control of the host it infects. The infected humans do not become zombies and retain their normal appearance. However, its depiction in the film is different, since in the games it doesn't typically grant immunity to injuries.

The character Becky was not originally to be hearing-impaired, but after an outstanding audition, the role was given to Aryana Engineer. She was scouted by Paul W.S. Anderson and Milla Jovovich, as they were impressed by her performance in Orphan (2009).

The first movie of the series not to feature the Cerberus dogs.

Suburbia is actually a recreation of Raccoon City as evidenced by a brief shot of a crashed helicopter just like in the actual Raccoon City in the second movie. The helicopter belonged to the local news station.

Leon S. Kennedy, a prominent character in the game series, was rumored to appear since Resident Evil: Extinction (2007), and Jensen Ackles was considered for the role in Resident Evil: Afterlife (2010). As no deal could be made, Leon was moved to this film, and the part went to Johann Urb instead.

Despite the fact that it is one of the first scenes in the film, Alice's fall in the water was one of the last sequences to be filmed. There was an extra shot of Jill Valentine and Umbrella soldiers pulling Alice out of the water which was cut in the editing process.

The original plan of Paul W.S. Anderson was to film this movie simultaneously with the upcoming sixth installment in the series, making essentially a two part finale. In the early stages of development Ali Larter and Wentworth Miller were slated to be included in the cast list. When the studio backed out of the concerted filming for two movies, Claire and Chris Redfield were scrapped from the production plans and the filmmakers made it clear that "Resident Evil: Retribution" would be a standalone film.

Although Carlos Olivera has a major role in the plot, Oded Fehr's name is curiously absent from the opening titles.

Matthew Mercer who voiced Leon S. Kennedy from the games and the voice used for the audition's reference audio, tried out for the role and didn't get it. He still finds the situation hilarious to this day.

The idea of using environmental simulations references the 4th game based novel Resident Evil Underworld by S.D. Perry, where there were 4 environmental simulations; a forest, a desert, a mountain, and a city.

Scheduling conflicts prevented Wentworth Miller and Spencer Locke from reprising their roles from the previous film. Ali Larter was unavailable as she had just gotten pregnant, but returned for the final film.

Won the Canadian Screen Award for Achievement in Visual Effects (2013).

There are 3 scenes from Resident Evil: Afterlife (2010) that were reused in this movie: 1. J-pop girl attacking Japanese businessman 2. The scene showing A serum flowing through Alice's veins 3. The Ospreys approaching the Arcadia to attack.

Is the only film in the series to feature characters Leon S. Kennedy, Barry Burton, Ada Wong, and Becky. Except for the latter, all of these characters appeared in the video games. Leon and Ada are the only Resident Evil couple to debut together and have their romance hinted at in the films.

Unlike the films, Barry and Leon are not partners. In fact, Barry and Leon have not appeared together in any canon-games or the CGI movies set in the same world as the games. Barry is a very close friend to the Redfield family (Chris and Claire especially). He appears alongside Chris in Resident Evil (1996) and Claire in Resident Evil: Revelations 2 (2015). It is possible he knows Leon in the games through Claire (Claire and Leon both debut in Resident Evil 2 (1998)). Chris and Leon know each other through Claire Redfield. However, they first appear together in Resident Evil 6 (2012), where the two already know each other.

The team considered redubbing Johann Urb's voice as Leon due to his Finnish accent.

Although not mentioned in the finished film the back-story reveals that the majority of the Umbrella soldiers are clones. This accounts for their vast numbers and explains their allegiance to Umbrella. The only time that this is hinted at is during the scene after the reboot in the facility systems. Jill Valentine is activated through the Red Queen and all the soldiers seem to wake up simultaneously.

Leon and Ada are the only Resident Evil couple to debut together and have their romance hinted at in the films.

The ending of the 4th film was shot on the exterior of a real abandoned ship. When it came time to film the opening sequence of this film however, the crew were surprised to discover that the ship had been back in use and therefore was no longer available. As a result the Arcadia battle was eventually filmed on a soundstage replica of the real ship.

In the scene that takes place in the Oval Office, the Great Seal of the United States on the ground is modified so that the eagle's head faces its left foot, which is holding 13 arrows (symbolizing war), as opposed to its normal pose where it faces its right foot holding an olive branch (symbolizing peace).

The first shot in the movie of Alice rising from the water is entirely CGI.

The idea of cloning the umbrella soldiers may have stemmed from a comment made in an audio commentary of the original Resident Evil (2002) film. Michelle Rodriguez said that Colin Salmon should be brought back in a sequel as a clone. Ultimately, this came true for Salmon as well as Rodriguez and Oded Fehr.

This is the first time in Resident Evil history that Jill and Leon have ever met. Canon or otherwise.  The next time will be Resident Evil Death Island (2023).

The demise of Rain was the fall in the icy water. It was Milla Jovovich's suggestion that the swimming zombies had to appear as well and it was added during production.

Michelle Rodriguez played a third character. Apart from her good and evil versions she also portrayed a zombie doppelganger. As Ada Wong explains Umbrella tests every clone in different levels of biohazard. The scene was cut in the editing process along with many scenes in the suburban house with Alice and her family, mainly because Paul W.S. Anderson reshot the former scene to feature Alice and Ada fighting the Axemen instead of the Zombie Rain clone.

An early version of the script reveals that the entire elite Unit that infiltrated the Hive in the first film were clones. This explains more fluently the reappearance of Rain and One. Although this subplot was eliminated from the film there is still a hint. Ada Wong explains to Alice that Umbrella utilizes 50 basic models for the clones by simply changing their memories and their predicament. Alice herself is one of the 50 prototypes. This information actually foreshadows the revelations about Alice's past in the sixth film.

According to the official novelization Alice intended to dock the Arcadia ship in the nearest island, Catalina. She believed it would be a safe place with few undead creatures. The trip was never realized because of the attack. The novelization clarifies that during the gunfire Alice lost the Redfield's from her eyesight and never knew what happened to them.

There was footage filmed of a flash back scene with Luther West wandering in the streets of Los Angeles until a chopper picked him up. He was an eyewitness to the Arcadia battle and the capture of Alice. This was the incentive for Leon Kennedy to save Luther. The crucial information about the imprisonment of Alice helped West join the rescue team. The extra scenes of Luther in Los Angeles were removed from the final cut.

The close-ups of bones cracking during the final fight are a direct reference to the X-Ray feature in Mortal Kombat (2011), which is also an in-joke because the movie's director, Paul W.S. Anderson, also directed the first game adaptation, Mortal Kombat (1995).

The film never reveals what became of Chris Redfield (Wentworth Miller), Claire Redfield (Ali Larter) and K-Mart (Spencer Locke) from the previous movie Resident Evil: Afterlife (2010), so it may be assumed that all three died in Umbrella's attack on the Arcadia with which the movie opens. However, Claire reappears alive and well in Resident Evil: The Final Chapter (2016), explaining that she managed to escape from Umbrella. There is no word on either Chris or K-Mart, so they may still have died in the attack, although the novelization of the final film explains that Claire saw Chris being safely taken away in a different helicopter, but she hasn't seen him since.

The fake name of Alice's husband played by Oded Fehr, who also reprises his role of Carlos, is never revealed in the film. The script and the film's novelization however reveal that his name is supposed to be Todd.

The Executioner scene was not scripted to appear in the film. However it was added during filming.

When Alice and Ada fight the two Executioners, one of them throws his axe and sticks it into a fuel truck. The label on the truck is "H. GORENSTEIN GASOLINE AND FUEL". Hartley Gorenstein is the production manager for this film.

The explanation for the end of the world caused by the T-Virus between the second and the third movie is retconned. Instead of the Raccoon City infection being spread around the world by rats and airliners, Wesker now claims that a global bio-weapons arms race fueled by Umbrella led to the end of the world, as every nation wanted the T-Virus for themselves. This is only one of several retcons, including the fact that Wesker is now alive and forced to be Alice's ally, and the Red Queen is also 'alive' and now presents the new main villain. The next sequel will retcon everything once again.

When Ada and Alice get to suburbia and Ada tells Alice about the clones.... She says "they can even be a soldier for Umbrella". In the last film it's revealed Alice is in fact a clone, who was a soldier for Umbrella.

The costume and brainwashing device that Jill Valentine (Sienna Guillory) wears on her person are taken directly from Resident Evil 5 (2009). The difference is that in that game, Jill is mind-controlled to ally with Albert Wesker (not Umbrella), and it is during a long fight with Chris Redfield and Sheva Alomar (not Alice, who hasn't appeared in the games) that they manage to remove the device, after which Jill comes to her senses again.

This is the second Resident Evil spin-off to feature Leon Scott Kennedy and Barry Burton working together in an "anti-umbrella" unit. The two also collaborated in the non-canon Resident Evil Gaiden (2001) for the GameBoy Color. Although, the story reveals that the Leon in that game was an impostor and the real Leon had died.

Among the test floors appearing in the holographic maps (like Tokyo, Moscow, Suburbia, etc) there is also a Berlin simulation that is never seen in the film. There was a brief sequence in a simulated Berlin in some drafts of the script, set to take place immediately after Alice's escape from the cell and before the Tokyo revisiting sequence, but it was eventually scrapped. Ironically, most of the first film Resident Evil (2002) was shot in and around Berlin.

After Leon and Luthor shoot Rain, when the bullets go down her arm and out of her fingers, you can hear the Las Plagas music from Resident Evil 4 (2005)

Bad Rain makes herself unstoppable with the Las Plagas parasite, ironically she later dies at the hands of several Las Plagas undead.

Mistakes

When Ada explains how she killed the operatives in the central command station, a security-tape replay shows Ada standing in the center of the room shooting outwards. But when Alice first enters the room, there are glass walls in front of each workstation, with blood splatters on the inside. This would imply that the workers were shot from behind. If Ada had shot from the center of the room, the glass walls would have been shattered.

At the end of the movie Alice lays flat on her stomach and rubs some snow off the ice to see an infected underneath it. In the next scene no disruptions to the snow are visible.

When the system has to reboot, a drawer opens revealing Alice's clothing for the rest of the film. When Alice walks into the hallway her shoes are a high wedge heel, while later in the film during combat scenes, Alice's heels change from high wedges to low wedged heels.

During the Arcadia battle the tip of the red plane in the air goes from whole to broken to whole to broken.

We see blood and bullets coming out of Rain's fingertips, but there is no blood in the snow.

During the fight between Alice and the Tokyo zombies in the well lit, white hallway, Alice shoots and smashes the zombies, with blood shown coming from the impacts. However no blood ever appears on the white walls until the end, when only pools can be seen on the floor.

The Japanese "J-Pop" zombie changes positions in many shots during the Corridor Fight scene, and in some cases disappears completely, then reappears at the end when she stands up again.

In the suburbia scene, a Chevrolet Impala police car is seen headed down the street behind Alice & Becky, which changes into a Crown Victoria in the very next shot.

Throughout the car chase, damage on the car disappears and reappears between shots.

During the attack on the Arcadia, Alice is seen shooting quarters from her 12 gauge shotgun through the windshield of one of the tilt-rotor aircraft, killing the pilot. However, the diameter of a quarter is 0.955 inches; therefore, it would not fit in a 12 gauge shotgun, as the diameter of the shotgun barrel is only 0.729 inches.

The Umbrella facility is located in northern Russia where the climate is shown to be arctic with snow, ice and heavy wind. However the characters have no problem with low temperature since they only wear evening dresses, no hats etc. Funnily the strike team wears bare t-shirts right after entering the elevator.

The car Alice and her daughter are in gets hit by a truck and flips over. That kind of an impact should have cause the car spin instead of flipping up.

During the fight between Leon, Luther, and Rain at the climax of the film, Rain's gloves seem to disappear in close-ups.

In the Moscow car chase a Las Plagas zombie is shooting at the heroes car with a DShK 12.7mm heavy machine gun. The bullets bounce off the car's trunk, while in reality they would go through killing the passengers.

Part of Ada Wong's outfit includes a Rosendahl Watch II digital watch, which seems to be acting as a more advanced smart watch.

One of the dead Umbrella soldiers is breathing (his machine gun rises and falls on his chest as he breathes).

Despite the fact that areas just outside of buildings should be as cold as the open areas, character's breath is not shown. If the temperatures were truly below freezing , the condensation from their breath should be visible.

Ada is discussing Becky with Alice she mentions that Becky's feelings towards Alice have been imprinted. Memories/feelings are implanted and NOT imprinted.

When the guy with the chainsaw starts attacking the guy in front of him the extra on the receiving end of this punishment can be verbally heard riling in pain, but in the close up you can see that his lips aren't moving.

After fighting the initial Tokyo dead in the Umbrella hallway, bodies are everywhere. When she finished off the J-Pop Girl, she see the horde coming for her. When the door opens & she runs for it, looking backwards from the door perspective, there are no bodies to slow down the undead.

During the opening sequence, as Raccoon City is shown on a 3d map, the view pans out to show the globe as the virus spreads, also showing earth as a mirror image, panning west from North America to Europe.

When Alice opens the attic door a crewmember's head appears at the lower left of the screen.

Milla Jovovich as Alice flubs her line in the opening narration when she pronounces Umbrella as "Umbreller" instead.

In Resident Evil: Afterlife (2010) J-Pop Girl is shown wearing high heels and has a purse around her body. In Retribution she can be seen wearing the purse again when in the Tokyo sequence, and footage is used from Afterlife implying she most likely has the heels on as well. However, when she is fighting Alice, her purse disappears, and she has no high heels or shoes on at all.