Continuity mistake: A few minutes before Quaid kills his "wife", there's a shot of her with bright pink lipstick. Immediately before he shoots her, her lipstick is burgundy. (01:03:10)
Continuity mistake: When Arnold Schwarzenegger and Rachel Ticotin are being attacked by the giant drilling machine, Arnie grabs a pneumatic drill and cuts the main oil line of the machine, getting the left side of his face and his shirt doused in oil. Yet throughout the remainder of the film, there is no oil on Arnie's face or shirt. (01:39:55)
Continuity mistake: When Arnie is giving his info about what his Mars woman should be like, there are two things to look at on the screen in front of him: The screen zooms in on the woman's face, cuts back to Arnie, cuts back to the screen when it zooms in on the face again. Also, look at the sequence when he's selecting her personality: "demure" is lit up before he mentions it. (00:17:35)
Continuity mistake: When Arnie uses the hologram projector in the alien reactor, there is a brief shot of him facing his own hologram image. Note that the gun and the projector switch positions in Arnie's hands - the bloodstain on his shirt's sleeve does not. (01:37:55)
Continuity mistake: In the escalator scene when Arnie uses a corpse as a shield, there's a close-up of Arnie's gun firing, and we can see there's blood on the side of the corpse's head. However, in the wider shots there isn't. (00:31:00)
Continuity mistake: When Sharon Stone cuts Arnie's left arm with the knife, he starts bleeding. Right afterwards he grabs Sharon's neck with his wounded left arm. When he lets go, Sharon's neck has no blood stains from Arnie's wounds. How come? (00:26:10)
Continuity mistake: In the scene where Michael Ironside's cronies are dragging Arnie to the service lift, watch Arnie's head: It changes from being flexed forward to being extended backwards as they swap camera angles. His hand positions change as well from shot to shot. (01:06:40)
Continuity mistake: Soon after the woman costume malfunctions, you can see the blue screen through the windows, which in the next shot is coloured orange.
Continuity mistake: When Arnie meets Bennie, he takes him to his cab and opens the door for him to get in. At that time, there's an explosion, and Bennie pulls the door down to shield himself and Arnie. The camera switches to behind them, and Bennie is just now pulling the door down. (00:52:50)
Continuity mistake: When Quaid finishes Gary and his fellow agents, the concrete wall behind him shows a bloodstain. The only opportunity for it to appear there would have been as Quaid hits the moustache man in the face; but this guy stands up again, and it doesn't look like he cracked his skull (which would have caused a stain). (00:22:30)
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)
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)
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)
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)
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)
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)
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)
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.
Answer: It's not a stunt double, it's a mannequin (fake head actually) of Arnie, used for the artificial head shot.
Grumpy Scot