Continuity mistake: Hatchet marks are already visible on the door when Vic Nottingham arrives to chop through it.
Continuity mistake: It was briefly stated in the second film that the T-Virus was created by Dr. Ashford to cure his daughter Angela and that the Red and White Queens were based on her. This movie contradicts that by suggesting that Dr. Marcus created the T-Virus to cure his daughter Alicia, and that the Red/White Queens were modeled after her. While the rest of the movie stays true to the continuity of the previous films, this rather obvious ret-con is still a major continuity gaff.
Continuity mistake: He cuts a hole in her pants for insemination. When in the car moments before fighting the dog there is no hole.
Continuity mistake: When the Senator is about to be sacrificed, the cloth on her mouth immediately disappears for a split second. (01:29:35)
Visible crew/equipment: In the second scene where the main character approaches the car, there's the filming crew visible in the right corner of the car's bumper. (00:02:30)
Factual error: The license plate of the car that takes the protagonist to the sanitarium is GR 36E46. That's not a valid Swiss plate: GR indicates the canton of Graubünden, but other than that it is supposed to have only digits and no letters.
Plot hole: Sang-hwa forces a zombie inside a toilet stall. The zombie begins to bang on the door violently and Sang-hwa has to hold onto the door in order to stop the zombie from getting out. However, it is revealed later on that the zombies do not attempt to attack the humans or react violently or aggressively if they cannot see them. If this is the case, then this scene of the zombie banging on the door even when it cannot see any of the uninfected humans contradicts the rules that are established later on. (00:25:48)
Continuity mistake: When Maddie is coming up with an ending to her novel, she opens one of the ending drafts. Not long after opening the draft, she decides to go on facetime and make a call, whilst the draft is still open, then the man she is trying to contact calls her back. She then closes the laptop and tidies up. When she returns and opens up the laptop, the draft that was just shown on the laptop has become a completely different one. (00:10:10 - 00:14:25)
Continuity mistake: When Nancy is surfboarding, she is going to ride her last wave for the day. When she is waiting for her last wave, the ocean appears to be calm, but when it cuts to the very far 3rd person view a big wave pops up on the screen. When it cuts back the wave has disappeared.
Visible crew/equipment: When Marcy tries to shoot the dog, you can see a crew member who picks him up at the left side of the little appliance room.
Revealing mistake: As Joe is gesturing, the wrinkles of the gloves worn to make his hands bigger are noticeable.
Revealing mistake: When Austin goes to write the Roman numeral "XVII" on the chalkboard, the erased numerals from a previous take are still visible where he's about to write it. (00:41:36)
Continuity mistake: The close-up view of the five stones on the rock was different from the distant view. The shape of the larger rock they were on had a dip in it (left-center) and had a bigger arc to the right. The five stones were arranged (spaced) differently even after accounting for the different angles and distances at which Mikey saw them. For example, the two stones on the left side were further apart and the two stones on the right side lined up more vertically. (00:06:13)
Other mistake: The tow truck driver says he has to repair the "split axle" before they can proceed. It wasn't clear what kind of truck he arrived in but the car could easily have been towed on the rear wheels on a wrecker and winched onto a flatbed.
Audio problem: The chef finally gets the bright idea to fire his hunting rifle at Morgan's fleeing vehicle. In a previous scene he was grabbing ammunition for his rifle, and he also loaded it. The rounds appeared to be high power rifle ammo, probably in the 7mm Remington magnum or .30-06 range, very common hunting rounds. When he fires his rifle it sounds quieter than a suppressed shot, however he has no suppressor on the muzzle end of his weapon. (01:09:20)
Continuity mistake: While Eddie performs "Hot Patootie", he's seated on the motorcycle with Columbia for a bit, and when Eddie stands up he's holding the mic in his left hand, but as he walks up the steps it's in his right hand, then next shot when he's facing Frank-N-Furter the mic is in Eddie's left hand, and next shot it's back to his right hand again.
Continuity mistake: The chef at the airport stabs someone, but the knife blade is clean afterwards; moments later he stabs it through the valise, and it is covered in blood.
Factual error: A bullhorn can be heard in the background off-screen during a battle with the zombies, even though the movie takes place during Victorian times. (01:19:30)