He's Too Sexy for His Fat - S2-E17
Continuity mistake: As Peter is about to demonstrate what he'd do to embarrass Chris next to the diving board, there is a blond woman in a purple one-piece behind him as Meg walks up. He grabs his nipple/moob, and then in the close-up just before he licks it, suddenly the blonde woman vanishes, and the people behind him multiply. (00:06:55)