The Penguin Declines (3) - S2-E39
Factual error: Joker, Penguin and no less than four henchmen all manage to hide in the Batmobile's trunk and leap out when it enters the Batcave. Even for Batman, this is stretching credibility more than a bit. There's no way the Batmobile's trunk could hold six adults and still close (and it was closed). Two might fit, even three in a pinch - but not six. (00:17:30)