Brother From the Same Planet - S4-E14
Continuity mistake: When Homer is showing Pepi the garage, it is purple. In the main titles and in every other episode, it is an orangey colour.
Brother From the Same Planet - S4-E14
Continuity mistake: After Pepi and Tom walk off into the sunset together it cuts to Bart handing Homer another beer, and the picture behind the couch has brown sails over the boat, but next shot it's colored properly with white sails. (00:21:30)
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.