Continuity mistake: When Principal Skinner is speaking to Marge and Homer, Homer is lying on the settee and you can see there is nothing beside it, but in the next shot his beer can appears from nowhere.
Continuity mistake: When Principal Skinner rings the doorbell of the Simpsons' house, the handle on the door is pink. But when Marge is at the door, the handle is now light blue.
Continuity mistake: When Principal Skinner and his mother are with Bart and his friends after the toilet prank, you can see Bart has Milhouse, Richard and Lewis are beside him. In one shot, Bart is on his own and the other three boys have gone, and in the next shot, they are back again.
Continuity mistake: When Maya and Moe are at Moe's home, Maya gives Moe a glass of water and he sits down on the sofa with the glass in his left hand. In the next shot, the glass has gone.
Continuity mistake: When Maya and Moe arrive at Moe's house, you can see there is nothing on the arm of the sofa, but in the next shot a remote control appears from nowhere.
Continuity mistake: When Moe is sorting out the flowers at Moe's bar, you can see there is nothing behind the beer taps on the counter, but in the next shot a jar of pickled eggs appears from nowhere.
Continuity mistake: When Maggie is swinging a spade at the other children in the playground, there is a tree behind her that disappears in the next shot.
Continuity mistake: When Homer is pushing Maggie along in her pushchair, Santa's Little Helper comes along and you can see that Maggie has a dummy in her mouth. In the next shot, the dummy has disappeared.
Continuity mistake: At the beginning of the episode, the doormat outside the Simpsons' house is green, but when Maya and Moe arrive at the Simpsons' house for their double date later on, the mat is now purple.
Tree House of Horror XII - S13-E1
Continuity mistake: In "Wiz Kids", when Milhouse is performing his trick at Springwart's Magic Recital, the trick goes wrong and he runs off naked, leaving his cloak on the floor. Later on in the scene, the cloak disappears.
Tree House of Horror XII - S13-E1
Continuity mistake: In "House of Whacks", when Homer attacks the tank, he puts the axe in the right hand side of the tank, but in the next shot the axe is now in the middle of it.
Tree House of Horror XII - S13-E1
Continuity mistake: In "House of Whacks", when the tools are attacking Homer, you can see one of the tools puts shaving foam on his face. But when he is walking down the stairs, the foam has gone.
Tree House of Horror XII - S13-E1
Continuity mistake: In "House of Whacks", when Homer is sitting on the settee, you can see his beer glass is empty, even though a few seconds ago it was nearly full.
Tree House of Horror XII - S13-E1
Continuity mistake: In "House of Whacks", when the dishes are cleaned, you can see by Marge's plate there is a spoon and a fork. In the next shot, there is now only a spoon, which disappears in the next shot.
Tree House of Horror XII - S13-E1
Continuity mistake: In "House of Whacks", when Marge has finished eating her meal, you can see a spoon on her plate. But when she is seen on the camera, the spoon has gone.
Tree House of Horror XII - S13-E1
Continuity mistake: In "House of Whacks", when Marge opens the door to the robotic salesman, you can see there is a green mat under the door. But when the salesman puts his foot between the door, the mat is missing, and in next shot the mat has re-appeared.
Tree House of Horror XII - S13-E1
Continuity mistake: In "Hex and the City", when the leprechaun knocks Marge's glass over on the table when she is eating her pancakes, the glass changes position between shots.
Tree House of Horror XII - S13-E1
Continuity mistake: In "Hex and the City", when Homer puts his spade in the ground when he is digging a hole with Bart, the spade keeps disappearing and re-appearing between shots.
Tree House of Horror XII - S13-E1
Continuity mistake: In "Hex and the City", when Lenny and Carl are crushed by the helicopter at the tavern, the liquid behind Lenny is white but changes to brown in the next shot.
Tree House of Horror XII - S13-E1
Continuity mistake: In "Hex and the City", when Homer, Bart, Lisa and Maggie are eating their breakfast at the table, they see Marge with a blue beard and Homer spits some food on the table. In the next shot, the food has gone, and when Homer goes to strangle Bart, it is back again.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.