Sex, Pies and Idiot Scrapes - S20-E1
Continuity mistake: When Homer has Snake cornered, the second rung on the ladder behind them is broken. In the next shot it's not broken, then it is again.
Sex, Pies and Idiot Scrapes - S20-E1
Continuity mistake: During the St. Patrick's Day parade, Bart is wearing a green shirt throughout the whole scene, but he's wearing his usual orange shirt when he says "Where's the IRA when you need them?"
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.