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'.
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.
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 edition process.
Every other Resident Evil film had a different composer for the soundtrack. This is however the first time that the music was written by the same people in two consecutive films. Tomandandy (a duo of composers) scored Resident Evil: Afterlife (2010) and returned to write the soundtrack for this film as well.
Las Plagas is a parasite in the video games. However its depiction in the film is not accurate, since in the games it is merely a symbiotic entity and not a microorganism which grants immunity to injuries as in this film.
The trivia items below may give away important plot points.
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.
According to the official novelization Alice intended to dock the Arcadia ship in the nearest island, Katalina. 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 Redfields from her eyesight and never knew what happened to them.