Revealing mistake: When Arnold begins to beat up and throw around the workers of the hospital, the African American worker is thrown into a window. If you look carefully you can see that the window he is thrown into is a different kind of glass than the other windows that surround it, indicating that this is not real glass. You can also see that none of the other window frames of glass on the inside of the corridor. There is just the metal frames covering the windows. In some shots later in the scene when the T-1000 is chasing them down the corridor you can see the bits of glass that were left over from before have disappeared.
Revealing mistake: When the two Terminators first fight in the steel mill, in close - up shots the T-1000 is played by Robert Patrick, but in medium shots it's a stunt double who looks nothing like Robert Patrick.
Other mistake: When the aqueduct chase has finished, and the T-1000 strolls out of the fire, the semi is hardly burning in the background. Considering that the semi has just violently exploded, and the small bridge it just crashed into was nearly flattened, it seems odd that it shouldn't be burning (very tricky to see, best use zoom in).
Continuity mistake: During the aqueduct chase the amount of damage to the semi-trailer truck changes repeatedly. Damage to the semi's grille is severe, then is not. This happens about three times.
Visible crew/equipment: Camera lights are reflected in the glass door in the shot behind Dyson as Sarah Connor laser-scopes him.
Visible crew/equipment: In the Cyberdyne lobby when the Terminator walks towards the SWAT team, you can see unexploded squibs (pyrotechnics) in the wall behind him to his left (before the shooting starts).
Continuity mistake: In the scene where the Terminator and John are at the pay phone John picks the gun off the floor, it's cocked when it's in his hand, but as soon as he passes it to the Terminator, it's not cocked any more.
Visible crew/equipment: In the escape from the hospital where the car is driving fast in reverse, the stunt driver's head is visible sticking up from inside the trunk driving the car from the back. It's too far back to be John Connor's head.
Continuity mistake: In the car chase just before the final encounter in the foundry, the T-800 slams on the SWAT van's brakes and the helicopter slams into it, crushing the choppers front. A second later it is in reasonably good shape.
Continuity mistake: When the SWAT van crashes through Cyberdyne's front doors into the lobby, it comes to rest with the rear doors closed. When Sarah and John Connor enter it, it's in a different position and the rear doors are fully open.
Continuity mistake: When the T-1000 is chasing John in the black tow truck, after the truck goes off the bridge you can see that the truck has two tall exhaust pipes behind the cab. Then right after the truck hits the 2nd old car it shows a shot from behind the truck and the pipes are suddenly cut off.
Revealing mistake: When the T-1000 is firing out of the hole in the windshield of the chopper, a close up shot shows that there is clear tape around parts of the window keeping all the little bits of glass together.
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.
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.
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.
Revealing mistake: When the T-800 is being attacked by the SWAT team in the Cyberdyne building, notice that in most of the shots (i.e. when he is being shot in the face, and also when the camera is behind him) Arnie has been replaced by a dummy. When the T-800 pulls out his gun and starts shooting the SWAT team, it's now back to the real Arnie, and notice how none of their bullets are now hitting his face and body, even though shots are still being fired.
Revealing mistake: In the scene when the T-800 first comes through the time machine, in the shot where he stands up. If you look towards the right side of the bowl shape that's melted into the ground, you can see that the bowl shape is actually above ground. There's a shadow being cast by it on the right side.
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.
Continuity mistake: When the Terminator smashes the driver's window of the blue station wagon, there is a large section of glass at the top of the door that is stuck in the runner of the door. In the next shot as the Terminator is closing the door, this same section of glass is now missing. Not enough time has passed in the shots for it to disappear and there's no sound of it dropping.
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.
Continuity mistake: When Sarah Connor throws the keys to a male orderly to distract him, Dr. Silberman is standing right behind him. Two shots later, we see the doctor several feet away. The time lapse between the two shots was only one or two seconds.
Revealing mistake: When the tanker truck (liquid nitrogen) is sliding along the ground the sparks can be seen not to be coming from directly under the tanker but ejecting from small canisters slightly higher up the vehicle.
Continuity mistake: When the T-1000 walks through the bars at the mental clinic, he gets his handgun stuck in the bars for a few seconds before removing it. In the close-up shot we can see the gun is stuck. But in the wide shot that precedes it, his gun isn't stuck at all. Actor Robert Patrick (T-1000) unconvincingly has his arm wrapped around the bar to make it look like his gun is stuck.
Continuity mistake: Immediately after the Terminator shoots the gate guard at the mental institute, there is blood on the guard shack wall. A few seconds later, the blood has vanished.
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.