Continuity mistake: When Robert Crumb is looking at Harvey Pekar's drawings for comic-book ideas while the two eat in a restaurant, the level of the drink in Harvey's glass switches between full and two-thirds full several times.
Continuity mistake: At Harvey's retirement party, there's a close-up of a decorated sheet cake with yellow frosting. The cake is about to be sliced: a knife enters the shot from the right side of the frame. Smears of yellow frosting show on the last few inches of the knife blade although the cake is intact and the knife has not yet touched it.
Continuity mistake: Harvey meets a former classmate, Alice, in the Elmwood Home Bakery. They talk in the bakery and continue talking while walking toward her car. When she drives off, the other cars that were parked in front of the bakery have vanished, although we didn't see or hear them leave.