Plot hole: Towards the end of the movie when Michael Douglas makes his speech at the White House, he is able to quietly walk out of the gates with no reporters anywhere trying to chase him down. Totally unrealistic (especially considering what had just happened). (00:03:03 - 02:13:40)
Deliberate mistake: You might be wondering where Terry suddenly comes up with Jolly Jack all of the sudden after escaping the lab. In the commentary, they say that the Joker, in his transmission to Terry in the lab, was supposed to be eating out of a candy jar with "Jolly Jack" on it, but couldn't have it due to time constraints.
Continuity mistake: When Profion approaches the wheel with the sword, the wheel is almost stopped with the white blob on the right. Shot changes to the wheel totally motion less and the blob is on the left.
Continuity mistake: Luke McNamara is handcuffed behind his back at the police station but as he is loaded in to the ambulance he mysteriously is cuffed in front. [The handcuffs inside are normal police issue handcuffs and outside as he's getting into the ambulance they're attached to a belt, normally used for criminals they consider dangerous.]
Continuity mistake: When Ray gives his girlfriend the present right at the start, her bag moves up her arm when the shot changes. (00:01:10)
Revealing mistake: When Jean Reno and Vincent Cassel approach the hanging body of Jean-Pierre Cassel in the doctor's house, the hooded killer can be seen standing to the left of the screen. [Not visible on the VHS version, but on the widescreen DVD].
Continuity mistake: In the scene in the mine, when the killer attacks the black guy, his miner's light is knocked off. A few seconds later when it switches back to him, he's wearing it again.
Continuity mistake: When the they first show the Evil Snow-Plough Man, he's chasing kids and they run off to the left side of the road as proven when the kid's sled gets crushed. However, once he's past, they all pop up from a mound of snow on the right side of the road.
Continuity mistake: When Agent Connolly first finds the bomb on the ship, he is knocked over by Iris, dropping his gun. In the next scene, when they are running up the stairs, he has the gun, which he forgot to pick up.
Continuity mistake: In the hospital scene, Audrey's mother is sitting down with the bed table to her left. We see her start to rise, but when the shot cuts, she's suddenly standing at the bedside on the other side of the table, with no time transition included for her to get there naturally. (01:57:30)
Continuity mistake: In the scene where the Dr is explaining that his daughter might be a lesbian to Helen Hunt's character, when they move over to the desk area Helen's arms move from both hands leaning on his chest to only one back to both.
Continuity mistake: Several times through the film the Crocodile changes size from the size of a 30 foot croc to the size of a miniature barn.
Continuity mistake: In the scene where Jody is with her boyfriend on his bed, as he holds her neck the shot changes and he is holding her shoulder. This repeats a few times.
Continuity mistake: When the drunk fat guy falls down in Dawson's flashback, his hat falls off, yet in the next shot the hat has reappeared back on his head.
Factual error: This movie is supposed to be set in the 80's as it says in the beginning of the movie, however, during many shots where the street is visible from the news broadcast center or the scene with John Travolta in the street, there are many cars which were not around. One of these cars, for example is a 2000 Dodge Intrepid.
Other mistake: The girls paint their van with brushes before heading off. When the van is being driven later in the film as they make their getaway, it's obviously been airbrushed, as it's too smooth a paint job.
Continuity mistake: In the beginning of the movie when the letters of "Univershell" rotate around the Universal-logo globe, Earth is pictured as preglacial one-continent planet. When it's pictured as a background looking from out of the UFO it's the regular spaceview of Earth.
Continuity mistake: When Dawn goes to see Dr. Parella when she has the urge to cut with the piece of mirror, she cuts in the stairwell and then throws the piece of mirror on the floor. There is a distinct smashing sound that would indicate the glass has been shattered, however when Dr. Parella goes to the stairwell, the piece of glass is completely intact.
Continuity mistake: During the chase scene at the end of the film, P. T. Boomer (a character cut from the film), can be seen on top of Diesel 10 during the shot where he enters a tunnel.
Continuity mistake: Harry stands on top of a building with a girl folding paper planes. The plane they fold is folded with a blunt front. He throws it off the building and then the plane flies, all of a sudden the nose is sharp, this is visible. (00:12:10)