Continuity mistake: As Kelso is walking out the door with the blue paint on his face, one hand is on the push bar for the door and the other hand is down. Cut to the shot of him walking out the door and now his right hand is pushing the door open and his left hand is just coming down from pulling the alarm wire above the door loose with no time for him to have changed positions.
Continuity mistake: In the beginning of the episode you see JD walking through the hospital with a huge pile of files in his hands. He see the women with the big breasts and looks after her until he sees her butt. The camera changes to JD where he is making a face in disgust. Look at the files. A few files from the top moved and it looks like they are about the fall off. JD turns around and the next shot is again at JD after he has turned around. Look at the files again. The seemed to be in perfect order, with all the files piled neatly on top of each other.
Continuity mistake: The first time Turk and Cox are talking in the gym, watch the man on the machine behind Cox. During the first shot of Cox, the man's face is obscured by the pulley for a pull down bar. Cut to Turk then back to Cox and the pulley has moved enough so that the man's face is now visible. Cut to Turk and then back to Cox for the third time and the man's face is blocked again. The viewing angle of Cox is the same each time so it is not a camera angle difference.