Continuity mistake: When John and Catherine are in the hangar at the runway, the Cessna's tail number is N3035C. When the plane is shown in the air, the number is N3973F. When they land, the tail number has changed back to N3035C.
Continuity mistake: In the cemetery scene when the Terminator uses a bazooka to fire a missile at the TX, the shot that shows the TX being launched up in the air and hitting a gravestone should have shown the car used by the TX and the road where the car was parked. In the next shot, when the TX gets up and starts to run after the hearse, the road reappears but not the parked car.
Continuity mistake: In the scene just after Kate Brewster's dad has been shot he says to go to his office. On the way there you can see his jacket is undone and you can see his shirt and tie. Yet when they enter the office it shows him sitting down with his jacket neatly buttoned up. For a guy who just got shot and is running from machines, I doubt he would worry about buttoning up his jacket.
Continuity mistake: When Kate gets the phone call in the middle of the night to goto the pet clinic, her phone is a white+blue Nokia 8310. Later on when she is calling from the back of the pet truck and it loses reception and the camera goes onto the phones, its now an all blue Nokia 51xx (I think) series phone.
Continuity mistake: As the hearse comes out from under the truck while they are trying to get rid of the Terminatrix, you can see that the windscreen is intact. But as they drive down the hill it's missing.
Revealing mistake: When they are driving the tundra after the big champion crane crashes, the Terminator gets in the truck. If you look closely, the truck's shifter is all the way in park.
Continuity mistake: When John crashes the Toyota truck into the rear of the silver Taurus, the car's bumper cover lands on the ground to the right of the car, between it and a parked car. When John drives away from the accident, he drives between the Taurus and the parked car, but the cover isn't there to be run over- it's now tucked under the Taurus at the right/rear corner. Then, as the crane smashes the Taurus, the cover is now well to the car's left, in the lane of opposing traffic.
Continuity mistake: When Arnold shoots the crane tires, the motorbike is shown to have a windshield. Right after when the T-X knocks him off the bike the windshield is missing. The next shot is the ambulance hitting the bike and the windshield is back.
Continuity mistake: When John and the vet arrive at the mountain in their Cessna, the sun casts a shadow straight under the plane. The very moment they walk through the door into the hangar integrated in this mountain (which in the film is immediately after they landed), their shadows are in front of them indicating a low sun.
Continuity mistake: When the Terminator is hitting the T-X with the fire extinguisher, she puts her fist up and punctures it so the Terminator chucks it down on the floor. We see it on the floor again, but when the Terminator is running towards the T-X you see where the extinguisher was but now it has vanished.
Continuity mistake: When the Terminator gets in the Toyota Tundra with John (after destroying the crane that the T-X was in), you can see that there is no seat belt in the seat belt holder. But when the Terminator is examining John for "brain trauma", there is now a seat belt in the seat belt holder.
Continuity mistake: In the scene when the TX, disguised as Kate's fiance, is in a car with the two policemen on their way to find Kate, the TX kills the police officer who is driving by sticking its hand through his chest. His partner sitting in the passenger seat immediately reaches for his gun, causing his seatbelt to slide off his right shoulder. Cut to a shot from behind him and the seatbelt is back on the same shoulder.