Audio problem: When Jerry goes over to open the jail cell door, the sound effect of jingling keys can be heard, however the actor isn't holding any keys. The jail cell door doesn't even have a keyhole.

Continuity mistake: When the family kisses Will goodbye and when he sits bummed out on the couch, the pool float around his arm switches position, going under his left arm, then under his right, then left again. (00:02:50)
Answer: No, it's not Whoopi Goldberg herself, just like that's not Prince or Ray Charles. The limo is filled with celebrity impersonators, but they're all uncredited and I could find out who played them.
Bishop73