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.
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)
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)
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.
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.
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)
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.
Continuity mistake: After Edgemar lets Lori in and closes the door, a moment later the door is open in the mirror's reflection.
Continuity mistake: As Quaid copies the name Melina on the paper, the writing is in heavy black ink. When he leaves the counter the writing is very light, nearly non existent.