Continuity mistake: Near the end when Christian Slater comes back with the orange sherbert Austin has no gun, and then in the next shot Austin has a gun but no sherbert. [There are two versions of the film - a US, and non-US version. Christian Slater appears in the non-US version in a cameo role for a couple of lines.]
Continuity mistake: When the Vulcan drill is shown being rotated, first of all, it's being rotated in the wrong direction - in the direction that would make the drill face upward. Of course they could be planning to make a 360, but why? Also, if you look closely at the people below and around the drill, you'll notice that shot is in accelerated pace - everyone is moving really fast, like in old silent films. The guys in front of the drill are looking back and forth from their pads and the drill extremely fast. I guess it was done to show the drill rotation nicer.
Continuity mistake: At the end when they are trying to stop the drill from going into the earth, Austin runs into the room and starts firing his gun. Each time he fires the gun there is a flash. If you watch, you'll see he fires 3 times, but there are only 2 flashes.
Continuity mistake: When Austin hears footsteps approaching the penthouse, he rushes into a chair in the living room. As Alotta is standing in the doorway, Austin says, "You seem surprised to see me--" Where Austin's arm is up near his face. But when the camera zooms in at, "Miss Fagina," his arm is gone.
Continuity mistake: At the end, during Austin's confrontation with the FemBots, he lights them all a cigarette. In one shot the cigarettes fly into their mouths. In the next shot they are gone and they are nowhere around them. The same goes for the cigarette in Austin's mouth. (01:14:00)
Continuity mistake: When Austin and Vanessa are riding the bus down the Vegas strip, the bus changes directions on the strip between shots.
Continuity mistake: In the bachelors' party, when the man takes the call his beer is a quarter facing the camera and when he comes back it's all the way facing the camera.
Continuity mistake: During Austin's dance with the fembots, one of them shows a spring popping out of the side of her head, while another shows her head spouting flames from the top. A few moments later, the heads start blowing up. The spring is miraculously gone, as well as the flames.