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. (01:18:55)
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. (01:22:25 - 01:25:50)
Continuity mistake: When the Terminator is slamming his fists again the truck trying to fight his new programming, the damage to the truck changes between each camera angle. Watch the passenger front tire collapse under the truck in one scene and then it's just at an angle on the next. (01:28:10)
Continuity mistake: When smashing the truck in the hangar, the T-850 hits it and it falls down so that the bumper is on the floor. When it shows the T-850 from John's POV, the truck is back up on its wheels, although the wheels are still damaged. (01:29:05)
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. (01:30:45)
Continuity mistake: When John and Kate are in the Crystal peak bunker, T-X smashes through with a helicopter, and there is an external shot of the chopper's rear blade spinning, but when T-X exits, the rear blade is gone, then in the wide shot of T-X it reappears. (01:32:35)
Continuity mistake: JC's leg was crushed by the T-X. After emerging from the elevator, he limps on the wrong leg. (01:36:00 - 01:36:55)
Continuity mistake: In the scene were John, Kate and the Terminator find the RV, when John says to Kate, that Scott's death wasn't her fault, she is sitting in the passenger seat of the broken down Hearse. Then in the next shot Kate completely disappears and reappears when the Terminator mentions the TX is going to kill Robert Brewster.
Continuity mistake: When the TX's crane is pulling away after destroying the building facade, it is seen from the high angle that the top of the cab is clean. When the crane is shown again the cab roof is covered in cables and other debris. Also note it remains this way until catching up with Connor in the Tundra truck and then the crane is clean like it was run through a car wash.
Continuity mistake: When Kate takes a gun out of the coffin at the cemetery, you can see she puts her finger on the trigger. In the next shot, her finger is back around the handle and not around the trigger.
Continuity mistake: The amber parking light lenses on the hearse are mismatched and change several times thoughout the hearse scenes (note the Cadillac crest on the left side lens).
Continuity mistake: In the crane chase scene, there is a point where the last remaining ambulance collides with the back of the Toyota. You see the ambulance back off and the right headlight is smashed and the housing is dangling. The headlights are also off. The scene cuts to the rear-view mirror of the Toyota. You briefly see the same ambulance with its lights on and both headlights are intact. Shortly thereafter, they cut to a behind-the-back shot of Arnold as the same ambulance starts to flip. The tail lights are on. It wouldn't be brake lights since there is no driver and the Terminatrix certainly wouldn't remotely apply the brakes.
Continuity mistake: During the chase scene with the veterinary truck and the terminatrix, the damage to the truck is constantly changing. In one shot the hood of the truck is bent upward, in the next shot it is straight and undamaged.
Continuity mistake: When the crane flips over the arm is missing when it is seen sliding across the road.
Continuity mistake: When the TX runs the crane through the glass corner of a small building while chasing the tundra truck, the flashing orange lights on the top of the cab are missing. These lights return on the next shot.
Continuity mistake: A headlight breaks loose on the ambulance after hitting Arnold's motorcycle. The next shot when the TX is looking in her rear view mirror, the ambulance has two flawless headlights.
Continuity mistake: The Terminator is following the crane at the rear corner when the TX moves the arm out allowing the hook to hit parked cars and telephone poles. During the overhead shot there is no Terminator behind the crane.
Continuity mistake: During the chase scene with Kate's truck and the T-X in the crane, the driver's door disappears and reappears several times.
Continuity mistake: During the chase scene when the T-X is driving the crane, the legs of the crane are out in some shots and retracted in other shots.
Continuity mistake: When the Terminator breaks into the van the broken glass changes from smashing it to getting in.
Answer: The difference there would be suicide vs sacrifice. In T2, basically what he meant is he could not commit suicide as it was against his programming. They had beat the T-1000 and had won, but it was too dangerous for Terminator to stick around and knew he had to be destroyed. But he could not purposely do it to himself as it was an act of suicide. However in T3, it was a sacrificial move. The goal of his actions was not to destroy himself, it was to take out the TX and prevent her from reaching John. He had to do this by any means necessary and made a sacrifice play by shoving his core into her mouth and blowing them both up. It wasn't suicide this way, it wasn't self termination. He was taking her out but caused himself to be collateral damage.
Quantom X ★
Also, after watching that scene again, I'm adding this little tidbit. The Terminator didn't actually die from the thing he did to the TX in that move. If you notice towards the end after the nuclear bombs go off, the fall out ash is falling down around its head and its eyes are still on, slowly fading away. It was badly damaged by its move, but the bombs in the end finished him off.
Quantom X ★