Whilst Dr. Cox is telling Turk that he has to believe he's the best at what he does, Turk is seen wearing a bandana. In the next shot, where Doug is on the floor under a corpse, Turk has no bandana.
During the course of the episode, the rascal switches many times from being armless to having armrests.
On the roof the rascal is seen driving itself over the edge. The rascal shown is a 600F, which requires the user to constantly hold down a lever to move the scooter.
When Dr. Kelso lifts up Doug's cast at the beginning of the episode, the elastic bandage is seen on the bottom of the cast, showing that it is fake.
The Janitor is following black tread marks on the hallway floor, but when he comes upon the scooter it has gray wheels. It would not be possible for it to leave black tread marks.
When Dr. Cox is looking at his reflection in the balloon, you can see a camera to his right.