Continuity mistake: When they finally arrive at the bottom of the sewer, Eddie's bandage is on a different cheek. (01:59:00)
Continuity mistake: If you look carefully at the monster (Frankenstein) you will see that his face is different in the ending scenes. The reason is, during the movie you see the monster take the woman doctor and throw her out the laboratory window. You then see the monster kind of stumble, which he really did and broke his ankle. So in the final scenes they replaced Lon Chaney Jr. as wolfman with a stuntman, and Lon Chaney Jr. finished the movie as the monster.
Continuity mistake: In the British Museum, when Rick and Ardeth are saving Evie, Rick gives her a .45 pistol and they start to shoot the guards, her pistol fires once and the slide locks back meaning the pistol had no ammo, but she keeps firing as if the magazine was still full. (00:39:47)
Continuity mistake: Hooper wears rimless eyeglasses, with the arms either attached at the upper corners of the lenses or at the sides of the lenses. If this didn't happen between shots within the same scenes, it could be presumed that Hooper has two different pairs of glasses and switches between the two, but they do indeed change between shots, such as when Mrs. Kintner slaps Brody, or even later, on the Orca. (00:36:05)
Continuity mistake: When the Senator is about to be sacrificed, the cloth on her mouth immediately disappears for a split second. (01:29:35)
Continuity mistake: When Frost has the head pure-blood vampire on the beach, after he pulls out his first vampire tooth you see blood all over his mouth, but when it shows the close up of him pulling out the other tooth, there is no blood. (01:04:22)
Continuity mistake: When Cheryl is running through the woods, she is wearing slippers that stay on up until she reaches the cabin door. However, in following shots, she is shown barefoot, and when Ash opens the door her foot is dirty as if she'd been running barefoot the whole time. (00:28:05 - 00:29:10)
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: About 10 minutes into the movie, when the truck is chasing the 2 college students in the car and starts ramming them, the bumper and the trunk is smashed in. The shot changes and shows the car's rear end and it is in perfect condition. This repeats at least 3 times.
Continuity mistake: Right after Bennett takes off in the plane, Claire throws a gun to Alice. Between the slow-motion shots, the gun switches position in mid-air before Alice catches it. In the shot of Claire throwing it, the barrel is facing to the right, meaning that it should be facing to the left in the shot of Alice catching it. But it still faces the right when she does. (00:58:30)
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: When Eddie falls through the floorboards, you can see his arm looks perfectly fine and is unbroken in a few quick shots. After the movie cuts back to him a few moments later, suddenly his arm is badly broken. (01:20:30 - 01:23:25)
Continuity mistake: In the shot of the alien's tail wrapping around the back of Lambert's legs right before it kills her, the floor is different to what it was before, there is water suddenly falling from the ceiling when there wasn't before and her trousers have changed from white to blue. This is because that shot was originally intended to be used when Brett was killed.
Continuity mistake: Mr. Furlong pushes Zeke into the fishing tank and it breaks, soaking him from head to toe with water. Moments later they are walking out and he is dry.
Continuity mistake: When Peyton returns to his lab after its destruction, a burnt picture of him and Julie is on the floor. The destroyed picture shows half of Peyton's face missing. After finding a new place to stay, when the picture is put into the scanner, more of Peyton's face is visible. (00:28:10 - 00:30:40)