Continuity mistake: During the test when they infiltrate the drug lord's camp and X escapes. In one scene before he leaves the barn/building to go outside and get the bike you see him get up and lean against the door twice. Once to get up and look outside to see one of the copters blow up a truck then it cuts to a reverse angle and you see him get up again to lean against the door.
Continuity mistake: After the Prague cop shoots at Vin Diesel and Yorgi, when they are in the garage, they chase him in the GTO. You see Diesel skid the car to a stop to shoot the cop, but when the camera pulls away, you see the car skid another couple of inches after it had clearly stopped before.
Continuity mistake: Just after X gets his new GTO and the cop knocks the window of the warehouse out, X and the bad guy jump back into the GTO. They drive out of the warehouse and the car is dirty on the bottom. If the car was spotless in the previous shot indoors, how did the car get so dirty so fast?