Revealing mistake: When Richter's arms get cut off and he falls down the elevator shaft to his death, you can very obviously see the outlines of his real arms inside his shirt when his leather jacket flies up as he falls.
Continuity mistake: When the man delivering the briefcase calls Quaid and tells him to go to the window, you see on the screen he turns to look to his side, but when Quaid goes to the window the man on the phone is still looking straight and then is seen turning to his side again.
Continuity mistake: When Quaid first arrives at The Last Resort, he hands Benny a tip and walks in through the front doors. In a front shot behind him is the head of a man outside who wasn't there a moment before when Quaid walked in.
Revealing mistake: During the scene when Quaid is escaping from Harry and his men, he slams two guys into the concrete wall behind him. The "concrete" wall shakes when the two men hit it. (00:22:25)
Continuity mistake: When Quaid uses the hologram, it's a mirror image of himself. However, before he enters the reactor room full of guards, we see him put the hologram device on his left wrist. His hologram (the one all the guards shoot at) has the device on his left wrist as well, instead of what would be the right.
Continuity mistake: When Quaid enters George/Kuato's private room in the rebel base you can see George's desk has a different arrangement from one shot to the other with Quaid's gun disappearing, a blue container swapped with a white on, the computer's screen having a cable plugged in or out and other objects moved around. (01:16:00)
Continuity mistake: In the scene where Quaid takes out Lori with a bullet to the head, she lands on the floor in such a manner that allows blood to run across the right side of her forehead. A few shots later Melina pushes Lori out of the way, repositioning the body on its opposite side. But once Richter discovers Lori moments later, blood is only visible running across the left side of her forehead. If anything, there should be blood running from either side of the bullet wound. (01:08:10 - 01:09:05)
Revealing mistake: In the last scene, when Douglas Quaid and Melina are holding each other and looking over the landscape of Mars while the sky gets colored, the camera starts from top behind them (looking down) then moves down while looking at them, so more and more of the Mars horizon gets visible. But the camera-tilt goes too far up, so at the top of the picture, you can see the blue-screen curtain and the pole and rings holding it. Douglas Quaid and Melina are just looking at a blue-screen. (This is visible on the video; on the DVD an extra black top-bar is covering it.) (01:48:55)
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: When Doug and Melina are being chased by Richter they leap from the catwalk in the big dome. When they reach the other side, from one camera angle, they grab the horizontal bar on the dome scaffolding. From the next angle they are holding onto the diagonally vertical bars swinging inward. (01:06:30)
Other mistake: When Quaid goes through the x-ray machine the first time, the person behind the man with the dog isn't shown to be carrying anything (there's no purple object shown). But then later the purple object is seen.
Suggested correction: Could simply be someone else with an item passing the person without any. He was walking very slow and certainly 1 person passed him, could be another one did as well.
Two people would have had to pass him and there's nothing to indicate 2 additional people were walking that much faster than him, or close to him.
They were off camera before. 1 person definitely did pass him so a second person doing the same is not unlikely.
They weren't off screen long enough.
I've seen this part multiple times. Who you see behind Quaid before entering the machine is first a woman with a handbag, then a man with mustache and case, then a blind man with a dog, after him a woman with a handbag again and more people. Now, the man with the mustache and case and the second woman with the handbag probably paused before entering the machine because we don't see them when Quaid passes, only the first woman with a bag, then a blind man with a dog and then a man with nothing. So both must have then sped up and then passed the man holding nothing. You see them walking faster than the others too. Not illogical when people are rushing to work or home either.
Continuity mistake: In the apartment, Lori grabs a knife, and after the first slice, switches the knife to her right hand. After the second slice, the knife can be seen midair as she tosses it from left to right again.
Suggested correction: It's not being shown tossed from right to left, you just see her spin the knife in the air to hold it in a different position.
Other mistake: After Arnold kills Harry and his gang at the beginning, how did that blood splatter get on the wall behind him to his right? He shot the henchman standing in that position from the back and the other who was shot was shot standing to the left side of the wall. So there is no explanation why the splatter is there.
Continuity mistake: Arnie has come back to the apartment after shooting his coworkers and asks Lori if this is a hallucination. He then reveals fresh blood smeared all over the palms of his hands but he had grabbed her before he asks the question. Lori is sitting in front of him without a drop of blood on her.
Visible crew/equipment: When Bob abruptly leaves his office due to Quaid's schizoid episode, a boom mic can be seen in a reflection on the glass, immediate left. (00:18:35)
Continuity mistake: During the chaos that ensues after Richter shoots out the spaceport windows, one of the rebels clings to a yellow pipe before being sucked into Mars' atmosphere. His hands are varying distances from each other, depending on the shot. (00:46:50)
Deliberate mistake: While Cohagen is on Mars, he calls Richter and chides him for trying to kill Quade. Richter is in a car on Earth, yet they're having a real-time conversation, which is impossible because of the distance. [While this is true, a movie with 4 to 21 minute pauses between lines would take rather a long time].
Suggested correction: This movie takes place an undisclosed amount of time into the future. Absolutely no telling what kind of technological advances could have taken place, in a science fiction movie at that.
Continuity mistake: When Quaid takes off his old woman disguise and throws the head to a soldier who catches it, the close-up shows that he's holding it beneath the ears. In the wide shot, he's holding it from behind the skull.
Revealing mistake: Sharon Stone gets shot dead, but she moves afterwards.
Continuity mistake: After Edgemar lets Lori in and closes the door, a moment later the door is open in the mirror's reflection.
