Continuity mistake: When John and Kate are in the bunker and they are talking about why they are there, we see John look down at the timer. It reads one minute 16 seconds. When Montana Civil Defense is talking over the radio, he deactivates it at 7 seconds. It should have read 27 seconds; there had been no breaks in the scene. (00:38:50)
Continuity mistake: When the Terminator and John are talking while driving the pet truck through the desert with Kate in the back, keep watching out the Terminator's side. In the distance, you can see about three huge cone-shaped trees and every time the Terminator talks, they're always in the shot. In one shot, there's about five, then it's always three again. (00:39:45)
Continuity mistake: When the T-850 walks around at the gas station, shopping, he fills up the shopping basket, and one of the bags of chips can't fit in the basket. However in the next clip, the basket is half empty and there is plenty of room for the two boxes of candy he grabs at the counter. (00:41:00)
Continuity mistake: In the scene at the gas station, Arnie removes the iron bar from the truck's doors and discards it. The truck drives off and is seen to have no bar holding the doors closed. There then follows a lengthy conversation between John and Kate. At the end of this conversation the truck is seen driving down a slight hill just before the scene changes to Scott's apartment- look closely and you'll see the iron bar on the doors, despite Arnie having removed it. (00:41:40 - 00:45:20)
Continuity mistake: When the Terminator is at the AM/PM, he is filling a small basket with various food items. One item in particular was a large bag of chips. The contents in the basket change from shot to shot, most noticeably the chips disappear completely. (00:42:35)
Continuity mistake: When John, Kate and Arnie are at the cemetery getting the weapons from Sarah's casket, Kate pulls a handgun on Arnie. He looks up and is facing his right with his legs turned in that direction. They go back to Kate and then back to Arnie. Now he is turned to the left. (00:51:05)
Continuity mistake: As Catherine grabs a pistol and shouts "Outta my way!", the Terminator stands up, with his left quarter profile towards her. After a cut to her, then back, his position changes to right quarter profile forward. (00:51:05)
Continuity mistake: At first, the color of the steering wheel of the police car (the one taking the TX disguised as Kate's fiance) is grey. In a close-up shot of the police officer looking at the TX's arm sticking through his chest, the wheel is now light brown. (00:52:50)
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. (00:52:55)
Continuity mistake: In the scene where the Terminator is carrying the casket out of the mausoleum, the police open fire from his left side. Close-ups show bullet holes on the front and top of the casket even before he turns to return fire. (00:54:40)
Continuity mistake: During the scene when Arnold carries the casket, a shot shows many bullet holes on its front side. Two shots later, these holes have disappeared. (00:54:45)
Continuity mistake: During the shooting scene at the cemetery, note one of the stones (rectangular from the left) behind T-101 when he comes out carrying a coffin. You can see it has 5 holes - 3 left, 2 upper right side. However, a few seconds later, it has 6 holes, but their position has completely changed, 3 upper side, 3 right side. (00:55:25)
Continuity mistake: During the scene with the hearse the front right hub cap comes off twice. (00:57:45 - 00:58:35)
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. (00:59:10)
Continuity mistake: The hubcaps on the hearse come off but are back on in later scenes. (00:59:20 - 01:00:30)
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. (01:04:40)
Continuity mistake: When John is threatening to kill himself, his finger alternates from being on the trigger of the handgun to being on the trigger guard from shot to shot. (01:04:55)
Continuity mistake: When the three leads leave the rest area in the mobile home to go find Cate's father, it's about 3.30pm (we hear reference to 6.18 pm and it's in 2 hours 53 minutes). After the conversation where T101 tells that he killed John, you see the car from the outside. You can see on the shadows that the sun is so low, it must be very close to sunset. Shortly afterwards, during the next conversation, it is bright daylight again and it stays so during the rest of the outdoors scenes. (01:08:20)
Continuity mistake: When John talks to Catherine while sitting at the table in a moving RV, watch the explosives he is working on. Position of the charges changes with every shot facing Catherine. At one point they completely disappear from the table leaving only the Glock 18 handgun, and just a second later the table shown full of explosives again. (01:09:55)
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. (01:16:40)
Answer: He was originally in talks - and by some reports, did appear on set for some period of time. While factual answers are in short supply (for obvious reasons), there appears to be a connection to his drug-use habits. For instance, he was checked into a hospital (LA Cedars Sinai) for what friends feared was a drug overdose in April 2001, and has been in and out of rehab over the years. Chances are the production company was unable or unwilling to get completion insurance.
Rooster of Doom