Continuity mistake: When Pacino asks a guy in a barbershop about Depp, the guy is being shaved, and the shaving foam is only on his cheek, but when he's at the doorway calling to Depp to come in the barbershop the foam reaches his temple, then back inside the foam is only at his cheek again.
Continuity mistake: In the run-away tram scene the camera shows a group of scared passengers. One of them, who is holding a real dog a few shots before is holding a stiff, stuffed dog and is waving it around.
Continuity mistake: When Jack is leaving the shed with the bug bomb, the canister switches from being under one arm to the other.
Continuity mistake: Between shots Grace goes from walking backwards to forwards, when meeting Bobby for the second time.
Continuity mistake: Peter walks into the bathroom holding a box of Chinese and a bottle of wine. He puts them down and hugs Sarah. She falls backwards into the bath and now he too is holding a glass of cloudy looking water. (00:08:25)
Continuity mistake: In the scene where Al Pacino and Keanu Reeves are on top of the office building, they walk to the right edge of the roof. When the camera changes from overview to close-up, they only need one or two steps to the edge, but they make at least six steps. (00:25:40)
Continuity mistake: During the first fight scene, the cyborg hunter has dark markings around his eyes. As soon as the fight moves indoors, the markings disappear completely.
Continuity mistake: During the scene when Martin and Cray are in the morgue, Cray throws the baseball bat at Martin. When Cray throws it it is upside down but when Martin catches it, it is rightside up. However, you never see the bat flip.
Continuity mistake: Concerns the helicopter carrying Bob Bishop to the White House. The helicopter is shown as having a wheel-chassis during the approach to the landing-site, and skis in the precise moment of landing.
Continuity mistake: When Mr. Eddie goes back to his Mercedes after beating up the "tailgate guy", the left side of the bumper on the Mercedes is damaged. When they drive back into the garage, we see the left side of the bumper is fine.
Continuity mistake: In the scene where Chyna decides she needs to fall down the stairs to break the chair she's chained to she's supposed to be handcuffed. As she starts to fall and tumbles down her hands are not handcuffed and fling around wildly.
Continuity mistake: When Wynn is talking to Al about the mission to blow up the plant, Wynn puts his cigarette out in the ash tray in the scorpion bowl and there are 4 butts in the ash tray, but a minute later when the camera shows the 2 scorpions fighting, the ash tray has no cigarette butts in it. (00:11:19)
Continuity mistake: During the gun battle Kiefer's car gets shot up by the police but during the entire drive afterwards, the car shows no damage.
Continuity mistake: Throughout the entire movie the size of the Event Horizon's interior versus that of its exterior is repeatedly off. Evidence of this is seen mostly with scenes that take place in the main access corridor. First off, it is made to seem that the ship has one central connecting tube, but in the exterior shots there are several tubes that make up the middle of the ship. This is pointed out when Miller is making his way across the ship to get to the air lock that Justin is about to open. Second, the length of the tube (heck even the whole ship) is too small in relation to how the ship appears from the outside. This is pointed out in a few different places in the movie - when the crew is up on bridge, then race all the way to the airlock in the middle of the main access corridor, where Justin has just closed the inner door and when the doctor is asked to go grab his med kit from medical, which is across the ship and he is gone only a few seconds, and also when Miller is running though the corridor to activate the explosive charges. Since the ship has no faster means of transportation, such as turbolifts or a tram system, they could not be covering the distance they appear to be covering in the movie.
Continuity mistake: At one point near the beginning when they're collecting the crew, Robert Carlyle is in the car smoking. He lifts the cigarette to his face and he's not wearing a glove. In the next shot he smokes again and he's wearing gloves.
Continuity mistake: In the scene where Dunn is collecting gear from the surplus store. The cops show up. When it shows a close-up of the cops in front of the cruiser the wipers are on, but then it goes to a distant shot and they're not on.
Continuity mistake: When Richard Gere's attorney tries to get into the murder scene apartment, the guard says to her (in subtitles) "if you mess up the murder scence [sic] you will be in some trouble". There is a typo in the subtitles.
Continuity mistake: In the last scene, Max's bathing suit changes color, from dark blue to light tan, back to dark blue.
Continuity mistake: In the end when the Kothoga is on fire and chasing Margo, it catches up to her in moments. However, everytime it dramatically changes angles, the Kothoga appears a lot futher away than it was previously, but soon after catching up once again. Noting her progress in the room, this situation is not simply replaying the same scene from different angles. Plus when she gets to the water tank, she has plenty of time to spare to hit a lever, climb the device, and jump in before the Kothoga looms overhead.
Continuity mistake: The downtown skyline keeps changing during the scenes where an asteroid segment is threatening Kansas City.