Character mistake: When they're on the island and the INGen helicopters are flying in, Jeff Goldblum takes the binoculars and looks through the wrong end. (00:32:30)
Visible crew/equipment: When Ashley is running down the corridors before escaping back into her medical room, you can see the dolly that The Engineer chasing her is being pushed on. (01:04:50)
Revealing mistake: When John Cusack is driving the actress, there is a shot looking over his right shoulder at the dashboard. The speedometer reads 0 mph. (00:08:15)
Deliberate mistake: At the beginning and especially at the end, Julianna Margulies spends extensive time in the ocean, wearing nothing but cargo pants and a T-shirt. Considering the movie takes place just off the Bering Strait, wouldn't she have quickly frozen to death? (01:21:05)
Continuity mistake: In the scene where Jonathan picks up the scarab, it breaks open and the beetle inside starts to crawl under his skin. We see Brendan Fraser tear Jonathan's shirt and cut the beetle out of him. However, in the very next scene, we see Jonathan walking into the temple, his shirt is intact and there is no blood to be seen. (01:37:05 - 01:38:30)
Other mistake: After Michael kills Laurie at the beginning, he hands the knife to the inmate with the clown mask. The next kill is the cameraman for which he uses the tripod ends. A few scenes later they show Michael standing holding a knife with fresh blood on it. He hasn't killed anybody with this knife yet so where did the blood come from?
Visible crew/equipment: At the start of the film, just after the war exercise, when the Sergeant begins yelling at the recruits you can see the outline of his microphone under his T-Shirt. (It's not his dog tags because you can see the shape and dog tags are not shaped like that.)
Revealing mistake: When Charley stabs Dandridge in the hand with his pencil, he stabs the hand holding him by the neck. The depth of the wound on Dandridge's hand reveals that the pencil should have stabbed Charlie in his neck and given him a severe wound, if not kill him.
Deliberate mistake: In the final shot of the film, Jill's head moves slightly when she's supposed to be dead. In the commentary, Wes Craven confirmed this wasn't strictly intentional, but he decided to leave the take in on purpose in case he decided to bring her back in a future installment. But unless a sequel proves she's still alive, it's technically a mistake, albeit a deliberate one.
Continuity mistake: When Mommie is cutting Christina's hair it keeps on changing from long to short several times.
Continuity mistake: At the start of the film, the dog is seen going from room to room looking for food. Just before he goes into Dana's room, someone can be seen through the crack in the door, moving from left to right.
Continuity mistake: James takes off his tie to cover the cut on Kristen's hand, but when they run outside to escape in the car James is wearing his tie again, then after the failed escape they run back inside the house and James tie is missing. In another scene Kristen goes into the woods to look for James and falls into a ditch, then as she climbs out the tie is missing from her hand, but the next scene it's back in place.
Revealing mistake: When Eric Matthews is smashing his foot, he hits it the first time and it shows a close up. If you watch the small amount of blood when he hits it again they have used the same shot. (00:04:00)
Revealing mistake: When the shark first attacks and bites off Jim's arm, you can see his real arm under his shirt as he's scrambling away from the water. (00:34:10)
Factual error: When Janet Leigh is shown lying dead on the floor of the shower, there is a close-up of her open eye. The pupil is contracted to a pinpoint (obviously due to the bright lighting) where it should have been dilated. After the film was released, Hitchcock heard from several ophthalmologists who pointed this out and suggested he use belladonna eye drops in the eyes of "dead" people in future films, as the chemical prevents the pupils from contracting. (00:48:30)
Continuity mistake: When John is driving to work and he hears Anna on the radio, he swerves to avoid a car. From inside the car you can see that there are no cars in the rear window, yet when the shot changes to an outside shot, there are 3 cars. (00:33:35)
Visible crew/equipment: In the scene after Patrick Bateman's second encounter with the detective in his office, we see Bateman having sex at Courtney's apartment. After he rolls off her, Bateman approaches the large, stand-up mirror in the bedroom. In the upper right hand corner of the mirror, a boom microphone can clearly be seen moving around to pick up Christian Bale's lines. The next time we get the same long shot, the microphone is gone. (00:52:45)
Visible crew/equipment: Near the beginning of the movie, the old priest is in Northern Iraq and you can see the shadow of a microphone on his hat.
Continuity mistake: When the old car blows up both of the dead zombies are gone. (00:21:40)
Visible crew/equipment: When Marcus attacks Simon at the loading dock, as Simon flies through the air after Marcus kicks him, you can see the face of Johnny Lee Miller's stunt double. (00:57:15)