Deliberate mistake: There are a number of things wrong with the roller coaster scene (besides the obvious impossibility of a crash like this actually occurring): 1) The restraints use ratchets to lock, not hydraulics. A coaster of this type wouldn't even have any hydraulic lines. 2) The attendants didn't check all the restraints. This is ALWAYS necessary, on ANY ride. 3) On any roller coaster, the Dispatch button (or "Start" in the movie) must be held down until the train is clear of the station. This is a safety feature to make sure the attendants are clear of the moving train. If the button is released before the train is clear of the station, it will stop. 4) At the bottom of the lift, the lift chain curves to follow the track into the station. This is impossible, a lift chain cannot curve horizontally, only vertically (normally at the top of the hill).