As Arthur is standing on the cop car after the crash with the ambulance, someone in the mob is holding a bat right in front of Arthur. The shot changes and there are no bat's in the air in front of him anywhere.
The idea that a late night talk show would air a video of a comic from a club just to make fun of his act in 1981 is just absurd. This type of thing did not take place until the modern smart phone age. In 1981 they would have had to have permission from both the comic and the club, and the act of airing it without permission would likely spark a lawsuit.