According to Box Office Mojo, the picture is ranked in the top twenty movies at the American box-office in the USA for the year of 1981, coming in at No. #20.
When Joe Braxton is hanging on the side of the bus as it begins to go down the hill, you can clearly see the cable of his safety harness attached to the rail of the bus.
When Braxton is sentenced to probation and being dragged out the courtroom, he grabs his coat. He is then dragged out the room. When he rushes back in and yells, you can see his coat lying on the floor outside. She he's pushed back outside the final time, his coat is in his hand again.
In several shots during the movie, the actors appear in the red interior of the probation officer's Cadillac Seville. At the end of the movie they flip flop back and forth between a car with red interior and a car with white interior. (Very obviously when Richard Pryor opens the door while sitting in car it is red, when he gets out it's white.)