Continuity mistake: When Arnie comes home after killing his workmate, he pulls Sharon Stone to the floor. From one angle his hands are on her shoulders, from another they're on her elbows. (00:23:45)
Factual error: Throughout the movie, whenever the domes are breached (which happens much too often) it is said that there is only vacuum outside. But Mars has an atmosphere. Its thin and mostly CO2, but it's there.
Suggested correction: While it is not a true vacuum outside the domes, it's around 1% of Earth's atmosphere. The effect of a dome breach would be close enough to a true vacuum to the people affected.
Suggested correction: "Vacuum" is a colloquial way of saying low pressure, just like the 'vacuum' you use to clean the house creates a low pressure to cause suction.
Suggested correction: It's possible human colonization of the planet affected the atmosphere.
If the Martian atmosphere ceased to exist, the sky would be always black, never red as seen in the movie (Mars' sky is actually a butterscotch color during daytime and bluish during twilight).
Audio problem: Just after Arnie accepts the cab driver's offer and the other one complains, Arnie's driver gives him the finger and says something like, "Eat this", but his lips don't match what he's saying. (00:52:45)
Continuity mistake: In the scene where Quaid and Melina are strapped into chairs by scientists, Quaid breaks out and stabs a bar into a guy's head using a downward motion. In the next shot, the bar is now coming up from the under side of the scientist's face and out of the top of his head. (01:30:00)
Factual error: When a person goes out into space, their eyes wouldn't be sucked out, their cheeks puffed, etc. They would have about 10-20 seconds of useful consciousness, when they could get back to a safe area. Even after that, they'd still be alive for about a minute, although unconscious. The only major problem that being in space for about half a minute might cause is rupturing the eardrums and possible blindness (although the eyeballs wouldn't be graphically sucked out). NASA's studies on this go back as far as the 1960's and were used by Stanley Kubrick during the making of 2001: A Space Odyssey. (00:03:50 - 01:43:20)
Revealing mistake: When Lori punches Doug in the crotch, you can see that Arnold Schwarzenegger is wearing some kind of padding under his pants to soften the blow. (00:25:35)
Continuity mistake: If you look closely at the position of Arnie's arms while still on the 3D screen, they are in a different position when he breaks through. (00:30:00)
Continuity mistake: When Arnie enters the hotel room on Earth, he receives a phone call from a man with a suitcase who tells him to look through the window. While Arnie is approaching to the window, we can see in the display that the mysterious man is looking to his upper right. In the next shot, when Arnie is looking through the window, we can see that the hotel room is located at the man's left side. (00:35:10)
Continuity mistake: In the airlock where Benny fires his machine gun at George, the lock handle behind Benny rotates on its own. (01:23:05)
Visible crew/equipment: When Quaid and Melina hop into Benny's cab and are being chased by Richter, watch Benny. During the shots where the perspective is from behind Benny, you can see that it is a stunt driver in the car. His head is shaved neatly, yet Benny's hair is curly and frilly all over. (01:11:00)
Revealing mistake: Right before Quade jumps on the train to get away from Richter, he uses a gun to break one of the train windows. His gun barely (if at all) touches the window and it shatters. (00:31:40)
Revealing mistake: When Arnie blows the old lady disguise mask on Mars Immigration, they shot him and the dome crashes. Right after the soldier gets sucked out of the room, some extra comes rolling and kicks the camera. (00:47:05)
Continuity mistake: When Doug is running from the bad guys after finding out what was going on from his "wife", he tucks his big gun in to his jacket pocket. When he is running through the scanner, that big gun is now in his pants. (00:28:15)
Revealing mistake: In the scene in the Mars Air/Spaceport, the troops are wearing Casio scientific calculators on their wrists. (00:43:50 - 00:46:55)
Revealing mistake: When Quade shoots Dr. Edgemar, Lori yells "Now you've DONE IT.", and the wall explodes, which is plainly made of foam. Many of the pieces of 'wall' tumble lightly across the floor. (01:05:40)
Continuity mistake: In the scene where Quaid unfolds a flyer for The Last Resort, he unfolds it with the flyer image facing the camera. When the scene cuts to him looking at it, the flyer image is facing him. (00:52:00)
Revealing mistake: When Doug and Melina are being chased by the drilling machine, it punches through a wall. When the machine comes out again it pulls some rocks with it, a very large one hits Melina and she doesn't even flinch, obviously because it's a fake rock. The size of rock should have knocked her to the floor or potentially killed her.
Continuity mistake: When Melina comes to the rescue of Doug, she starts shooting his captors. He drops to the floor, then in the next shot, he drops again. Doug also wakes up on top of a dead guy who had landed much further away from him before. (01:04:15)
Factual error: Martian sky is very inaccurate in the movie. It is depicted as much darker and redder than it would be in real life (Mars' sky is a butterscotch color during daytime, bluish at sunrise/sunset and far brighter than in the movie). Also, both of Mars' moons are very small, asteroid-like bodies and would appear as tinny star-like points of light to an observer on the surface of the planet.
Continuity mistake: During the hallway fight sequence between Lori and Melina, we see Quaid in the background aiming a machine gun - just as Melina gets kicked in the back. But a few seconds later, Quaid reaches for the same gun a second time. (01:07:40)
