Homer vs. the 18th Amendment - S8-E18
Continuity mistake: Carl and Lenny are seen at both Moe's and at the St. Patrick's Day parade, which are happening simultaneously.
Brother From Another Series - S8-E16
Continuity mistake: Reverend Lovejoy is standing behind Sideshow Bob during his speech, but in one shot, he is standing with the protesters, then back behind Bob.
Brother From Another Series - S8-E16
Continuity mistake: While Sideshow Bob is walking out of prison and towards the protesters, Carl's hair is red.
Audio problem: Marge, Bart and Lisa are still heard "oohing" at the plumbing supplies store even after they close their mouths.
Continuity mistake: After Marge bites the candle down to a smaller size, the candle turns back to its original size for a frame.
Continuity mistake: During Bart's stand-up comedy routine, Dr. Nick is seen wearing his usual white lab coat, but in the very next shot of the audience laughing, he is not wearing a coat.
Revealing mistake: While Larry and Homer are talking about Mr. Burns, Larry's drink flickers light pink twice.
Much Apu About Nothing - S7-E23
Continuity mistake: During the party for Apu, Dr. Nick is first seen not wearing a coat, then he has his usual white coat, then he has a brown coat, and then the white coat again.
22 Short Films About Springfield - S7-E21
Revealing mistake: A black line briefly appears on Apu's forehead while he's tossing the tofu dog around.
Audio problem: When the car drives into the cornfield, Martin is heard screaming, even though he is still asleep.
Continuity mistake: In the overhead shot of Patty smoking, she is sitting on a greenish-gold car, the car then turns blue in the next shot.
Continuity mistake: When Homer gets up to make Mr. Burns' breakfast, Marge's nightgown is yellow, making her look naked, but in the next shot, her gown is purple.
Continuity mistake: At the funeral, while everyone is clapping for Bob Newhart, Mayor Quimby is seen with brown skin.
Scenes From a Class Struggle in Springfield - S7-E14
Audio problem: Homer's mouth is completely out of sync when he says "our savings?"
Team Homer - S7-E12
Revealing mistake: When the children are running down the hallway, the animation keeps repeating. Duplicates of the same children are running several times.
Three Men and a Comic Book - S2-E21
Audio problem: When Homer offers to take the family to Krusty Burger, Lisa is heard cheering, even though her mouth is closed.
Ned 'N' Edna's Blend - S23-E21
Revealing mistake: When Marge is talking to Helen Lovejoy about Canapés at the party, Marge's mouth disappears for a single frame.
Continuity mistake: After Moe yells at Ralph, there's a woman in the background staring at Moe with an angry look on her face. She turns her head away from him after some seconds, but in the very next shot, she is looking at Moe with the same expression on her face.
Continuity mistake: When Milhouse snitches on Bart, Martin has grey hair and a black suit. In the very next shot he has his ordinary hair and is wearing a brown suit.
Continuity mistake: Jasper's beard is missing when everyone is singing "In-A-Gadda-Da-Vida" at church.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.