Continuity mistake: The T-1000 punches his body through the window of a helicopter to get inside. An instant later, the hole in the windshield is gone.
Continuity mistake: When the T-1000 is driving the truck, he drives off a bridge and the windshield pops off, but in the next scene the windshield is back.
Continuity mistake: When the T1000 is chasing John, Sarah and the T800 out of the hospital, the license plate on the cop car changes several times: from 999273 when we first see it to 999232 when it actually stops, then to 999001 after it jumps the grass verge, then from 999013 when it starts going straight, to 999018 when the T-1000 latches onto it.
Revealing mistake: When the Terminator's arm is caught in the wheel and he rips his own arm off and stands up, if you look closely (slow motion can help, but isn't essential) you can see his real arm stretched behind his back under his leather jacket.
Continuity mistake: The scene where John and his buddy hack into the ATM and get cash, John is telling his friend his mother is a psycho. Watch closely as John puts on his backpack twice.
Visible crew/equipment: In the scene where John, Sarah, and The Terminator are in the Cyberdyne building. They have just come down in the lift into the lobby where the SWAT team are waiting and firing gas cylinders. Arnie says his "I'll Be Back" and walks out of the lift. The SWAT team issue various instructions, then say "Ok - drop him!". Now - look carefully. The second they start to fire, look at the SWAT member who is furthest to the left and standing up. If you look right by his shoulder as soon as they start firing, what looks like a crew member walks into the scene, with his hands in his pockets!
Continuity mistake: If you watch carefully when the T-1000 has driven off the bridge in the truck, you can see the suspension and steering gear collapse and shift (severely) to the driver's right. A moment later, the alignment is perfect.
Revealing mistake: When the Terminator is trying to save John from the T-1000 in the truck, he makes the jump. If you look at his face and hair while he's airborne, you can clearly see it's a stunt double. The Terminator stunt double is also obvious in other shots throughout the film.
Continuity mistake: In the scene where Sarah Connor shoots Dyson in his house, it pans back and forth from him to her. In each shot of Dyson in his living room, the magazines on the coffee table are scattered, then stacked, then scattered again. Also, if you look at the blood on his shoulder, it is very heavy in one shot and very scarce in the next.
Continuity mistake: When the T-1000 drives his bike throught the glass of the Cyberdyne Systems building to get onto the helicopter, the windshield falls off. When you see it drop to the ground, it's still attached to the bike.
Continuity mistake: In the scene where the T-800 and the T-1000 have their first shootout in the mall, John Connor begins to run down a series of stairs to get to his dirtbike. Every time he passes a door it reads the level he's currently on. You will see he passes level 2 twice.
Continuity mistake: When the Terminator is riding the Harley chasing Young John Conner, John is down in the reservoir and the Terminator is up on the ledge, as he approaches the end of the wall, through the Terminator's point of view on the bike you see the wall end, it clearly extends to a point, on the very next scene as he makes the jump the point has all of a sudden gone from a point to a squared off edge. Obviously the jump would have been a disaster if the edge was pointed.
Continuity mistake: During the bar scene, when the Terminator is stabbed in the chest. If you pause the movie just after the rubber knife, you can clearly see that he gets stabbed right exactly above his right nipple. Later on when he goes in the kitchen to get the biker's keys, the cut with blood dripping appears on his ribcage far below the nipple.
Continuity mistake: In the scene where Sarah has just shot Dyson and she is crying against the wall, John comes up to her and starts hugging her. Every time the scene changes back to the hugging, look at John's watch. The time changes every time.
Continuity mistake: Towards the end of the film, when the T-1000 controlled police helicopter bears down on the SWAT truck, Sarah tries to gun it down and the T-1000 returns fire. Look carefully at the shots of the back of the SWAT truck, and notice that the bullet marks made by the T-1000 on the closed door keep changing between shots.