Revealing mistake: When the T-800 and T-1000 first begin to fight in the steel mill, the T-800 puts his fist through the T-1000's head causing him to revert to liquid metal form, then as the T-1000 is throwing the T-800 from side to side you can obviously tell that the T-1000 is just an actor wearing a highly metallic mylar suit in some shots. (02:14:10)
Continuity mistake: When Sarah carves "No Fate" into the desk, the tip of the knife curves toward her, then you see it facing away, then when John grabs it from the desk its tip is back toward him. (01:32:45)
Continuity mistake: When the Terminator drives the police van into the Cyberdyne building to rescue Sarah and John, one of the van's mirrors becomes crushed in on the side. Once the van is onto the freeway the mirror is intact again. (02:00:30)
Revealing mistake: In the scene where John is helping Arnie up after the T-1000 has been exploded and sent to his doom in the fiery pit of molten steel (Arnie is saying "I need a vacation"), you can see how the effects crew haphazardly put on a fake busted mechanical arm underneath Arnie's coat and how it bulges out from his shoulder. You can almost see how they just tied Arnie's arm back behind his back and put a fake arm over him. (02:23:35)
Continuity mistake: When the T-800 grabs the shotgun off the bar keeper,he cocks it (fully), then in the next shot, you see him half-way through cocking it. (00:09:30)
Continuity mistake: About halfway through the aqueduct chase, the T-800 shoots the semi in its left door. The hole stays there until a little before the end of the chase. (00:36:30)
Revealing mistake: Early on in the film, the T-800 sees John riding down the aqueduct. He stops, and a blue car skids and is hit by another on its right side near the rear wheel. As the T-800 sets off in pursuit of the T-1000 and John, a blue car skids and is hit on its left side. Guess what? Its the same car as earlier. You can tell by the massive dent above the rear wheel. (00:29:20 - 00:34:40)
Continuity mistake: When the T-800, Sarah and John are escaping the mental hospital in the elevator the T-1000 stabs through the top and cuts Sarah in the back. Later when are driving away from the hospital in the police car Sarah hugs John. When the camera shows Sarah's back her shirt is torn but the wound itself is gone. (01:03:10 - 01:06:45)
Factual error: When the Terminator is running from the T-1000 and the T-1000 shoots into the Terminator's back he shoots 26 bullets. That's impossible, the gun he is using is a Beretta 9 mm - even if double stacked it is impossible. (00:59:30)
Continuity mistake: When the SWAT van flips over you can see the many bullets holes on top of the Van. However a few frames later the bullet holes change from many to just a few. (02:04:30)
Visible crew/equipment: When the Terminator is catapulted into the factory by the tanker truck, wires are visible holding him up (Slow-mo or pause might help.). (01:52:50)
Other mistake: Just after the top of the truck's been sheared off, the T-1000 sticks his head back up and pushes the shattered windscreen out. He then steers quite severely right, then left, but given how narrow the area is he's driving down, that would have slammed him into both walls. (00:35:25)
Revealing mistake: Toward the end of the aqueduct chase, the T-800 pulls John off the bike and it is crushed by the semi. The camera jerks upward as John is pulled off, and you see that Robert Patrick has been replaced by a stunt double who looks nothing like him. (00:37:35)
Continuity mistake: The computer that the T-1000 reads in the police car (at the beginning) reads that John is 10 years old and was born in February of 1985. Which means that the movie would have to take place in 1995 (2 years before Judgment Day). Yet Arnold claims in the car, (while driving towards Mexico) that Judgment Day would happen in 3 years, just after the Skynet funding bill is passed by congress. (01:14:20)
Visible crew/equipment: When Sarah opens the car's door at the gas station a man is reflected on the window who shouldn't be there.
Continuity mistake: At the mall, after the Terminator has been thrown through a glass window shop, a man in grey pants approaches him from behind. When he stands up the guy has disappeared. (00:33:10)
Character mistake: When the T-1000 comes from the checkerboard floor and turns into the security guard at the mental hospital, the guard has just gotten a cup of coffee. On the side of the cup he has Jack, Jack, Ace, Ace. He looks at the bottom and says he's got a full house, but the card value on bottom of cup is Queen, which leaves him with only two pair.
Continuity mistake: In the shot where T-800 arrives in the time bubble, the bubble removes a clean cut chunk of the rear end of the truck. If you look at the very center of the wheel that is cut in half, there is part of the axle right at the tip of that wheel which is not cut. (00:06:25)
Continuity mistake: In the scene where the T-1000 disguised as John's foster mother, stabs Todd (foster father) through the mouth, she is standing at the table facing it. When it transforms back into its default form, it has moved away from the table completely. This is so that it can walk forwards (out of the shot) without having to walk around the table. (00:41:55)
Continuity mistake: When the T-800 arrives between the tractor-trailers, you can see a bumper sticker (i.e. "Vehicle makes wide turns") on the back of the trailer when the sparking begins. When Arnie arrives in the bubble it "melts" out the back corner of the trailer, and the sticker is no longer there. (00:05:50)