The often-used extra known as Big Ears is seen in two places at once during the scene in Arnold's when everyone is waiting for Fonzie to arrive.
The pitcher of lemonade Joanie makes goes from full to practically empty after pouring only one glass.
When Fonzie returns to Arnold's, everyone is waiting to see how he reacts to learning Richie fooled around with his girl. However, it's never really explained how every kid in town found out about that. Ralph and Potsie knew, but one can assume they wouldn't tell. Fonzie's girl Denise herself could have told people, but again it's never made clear.
Fonzie tells Richie that he's going to a demolition derby representing his garage and he gets to "drive the lead car into a brick wall." Later on, Richie tells Fonzie's girlfriend Denise that Fonzie will be driving into a "blank" wall.