Other mistake: When a man destroys the clown's bike, the clown jumps away, and he says "Where'd he go" and the clown comes back with boxing gloves on his hands. There is no way for the man to not see where he went since he kept his eyes on the clown the entire scene.
Suggested correction: The clown jumped up into thin air and disappeared for a couple of seconds then reappeared. The clowns are from "outer space" so they may be able to travel at super speed when they want.