Continuity mistake: While Moe drives his car during the traffic jam, the car's rearview mirror repeatedly vanishes and reappears.
Tree House of Horror X - S11-E4
Continuity mistake: When the possible witnesses of who may have seen the Simpsons kill Flanders, Homer is shown pointing at Marge with his right hand, but the next shot shows him pointing with his left hand.
Deliberate mistake: Lou and Eddie are driving Bart around in the cop car. Bart asks when they're going to shoot people. The shot cuts to Lou, who is driving. The entire frame of the car disappears around him and it's just him superimposed over a background. The shot cuts again and the frame is now visible. Even if it was a low-angle shot, you'd still see the roof of the car.
Tree House of Horror II: A Simpsons Halloween - S3-E7
Continuity mistake: When Mr. Burns is telling the robot Homer that he is his daddy, Burns is to the right of Homer, but after the POV of Burns' face (he is still oriented right of Homer) by Homer, Burns is now to the left of Homer.
Krusty Gets Kancelled - S4-E22
Other mistake: When the Red Hot Chili Peppers are performing on Krusty's TV special, bassist Flea is playing a standard electric guitar.
Continuity mistake: When Homer ignores Lily, she gets upset then runs out of Moe's, and in the interior shot the door is hinged at the left, but in the next exterior shot that door is hinged on the opposite side, while Lily is crying outside. (00:09:35)
Continuity mistake: When Marge walks out of her aunt's house onto the porch, the screen door's handle is at the right side, but in the following shots the screen door opens the opposite way. (00:10:05)
Continuity mistake: While Lily continues to "light up all the men's lives, except Homer's," when she walks into the power plant with picnic lunches, Homer is wearing a solid peach colored tie, but in the next shot it's a striped peach and pink tie. (00:11:00)
Continuity mistake: When Homer takes Lily home after her date with Burns, as Homer pulls up to her house, the doorknob is on the left side of its front door, but when Lily enters the house, the doorknob is on the opposite side of the door. (00:16:20)
Continuity mistake: At the end, when Lily is back at a pub in England and meets Homer's doppelganger, his single shirt pocket and button are at his right side, but as he and Lily leave the pub arm in arm his shirt pocket and button are on the opposite side. (00:20:20)
Homer Alone - S3-E15
Continuity mistake: When Homer is singing to Maggie, he is standing by the bed. But in the next shot, Homer disappears and reappears.
Continuity mistake: Seymour's time as a POW in Vietnam changes throughout the show. One episode he mentions having been one for a year and a half. Another one he says it was two years. A third one he says it was three years.
Continuity mistake: When Tony Hawk and Homer compete against each other on the skateboards, Bart is on Tony's starting side. When Homer knocks Hawk off his skateboard, Bart is now on the side that Homer started on.
Clown v. Board of Education - S34-E21
Continuity mistake: Fat Tony burns Krusty's tassel on his graduation cap. This causes Krusty to put it out and move it behind his head. In the next shot, it jumps back to the right side of the hat.
Character mistake: When Hugh proposes to Lisa using the electronic signage, he spells the word "honor" using the American English spelling. Hugh should have used "honour" as this part of the show was set in England, and Hugh is from England.
Other mistake: During the Planet of the Apes musical final number, as the chorus line dances on stage from left to center with the Statue of Liberty in the background; however, parts of the Statue (the pink background between arm and book) cut off the dancer's head as if it is in the foreground. (00:12:19)
The Nightmare After Krustmas - S28-E10
Continuity mistake: When Krusty is in the hospital, the style of his bed rail changes. (00:04:20 - 00:05:35)
The Nightmare After Krustmas - S28-E10
Continuity mistake: When Homer moves Maggie's crib closer to the gnome, the wall outlet under the light switch has nothing plugged in, but in the next shot as Homer exits the bedroom, a nightlight is suddenly plugged in. (00:10:20)
The Nightmare After Krustmas - S28-E10
Continuity mistake: While Krusty is in the hospital talking to Sophie, he pops the IV line from his arm so the tubing hangs down from the fluid bag. But when Krusty tells Sophie that he knows she's reaching out, suddenly Krusty's IV line is properly inserted in the cannula again, only to change back to the tubing hanging down. Also, the white pillow propping up Krusty's foot vanishes and reappears during these shots. (00:05:15)
The Nightmare After Krustmas - S28-E10
Continuity mistake: When Bart opens the door for Krusty and Sophie, Bart is standing on a floor mat, but in the next exterior shot, that indoor floor mat has vanished. Other changes include the cane's handle within Krusty's grip facing the opposite way, as well as Krusty's and Sophie's positions at the outdoor purple mat. (00:06:50)
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.