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Revealing mistake: When everyone is cheering for Ned at the neighborhood watch meeting, Apu's hand is yellow.
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Revealing mistake: When Homer is on the news talk-show talking to the cat burglar, he puts his hand on his chest and the opening of his shirt appears over his hand.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.