Continuity mistake: In the new opening credits (from Feb 09) when the camera is zooming into the bullies cutting the head off the statue Ralph Wiggum is nowhere to be seen, but when the head falls off, it lands on Ralph. (00:00:10)
Continuity mistake: When Maggie goes through the checkout at the beginning, Marge's trolley is grey and has a red handle. But in the next shot, when Maggie pops out of the bag, the trolley handle is turquoise. (00:00:30)
Continuity mistake: In the introduction, initially Maggie's seat is light purple. However, in the wider shot of her and Marge, the seat changes to a burgundy colour. (00:00:50)
Continuity mistake: In the title sequence Mr. Largo has a baton in his hand when conducting. This disappears as he stops conducting to throw Lisa out. (00:00:50)
Continuity mistake: In the old main title sequence, when Homer gets out of his car, the door inside the garage is red, but when he is screaming and running towards it, it's now brown. (00:01:40)
Factual error: During the theme, the Simpsons' mailbox flag is on the wrong side of the mailbox. (Flags are always on a mailbox's right side, when viewed from The Front. The one at the Simpson home is on the left side of their mailbox). (00:01:45)
Continuity mistake: This is a mistake for the introduction from seasons 2-20 (1991-2009). When Homer screams, he turns round. You see this in a wide shot. There are no boxes to the right of the door in the garage. However, two just appear out of thin air when he runs through the garage. (00:01:50)
Continuity mistake: When Bart leaves the school, you can see that his skateboard is green and perfectly flat. But when he is skating through the crowd and past the people at the bus stop, the skateboard has an orange stripe down the middle and is raised at the rear.
Revealing mistake: In all the intro scenes from season 2 to season 20, episode 9, in the wideshot where Bart skateboards out of the school, if you look closely, part of the sky can be seen on the ground. (This mistake may only apply to the original format).
Continuity mistake: On various occasions The Front door, viewed from the inside of the house, has hinges - and therefore opens - on the wrong side, if you compare it to the shots of it from the outside.
Continuity mistake: In the new opening sequence, Kearney and Dolph cut off Jebbidah's head. But in the pan of the city, the head is back.
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.
Revealing mistake: During the intro to some earlier episodes where Bart leaves the school, the scene pans down and the edge of the animation paper can be seen in a couple spots at the very bottom of the frame. It is blue in color. This error persisted through many seasons.
Continuity mistake: When the women of the neighbourhood throw Marge a baby shower because she's pregnant with Maggie, Ruth Powers is one of the ladies there. Ruth only met Marge when she moved to Springfield with her daughter in "New Kid on the Block" (Maggie was already born in the episode).
The Simpsons Christmas Special: Simpsons Roasting on an Open Fire - S1-E1
Revealing mistake: When Marge is speaking on the phone to her sisters, her sisters say something that sounds like they said that Homer is ugly. Marge then puts down the phone wire that she was curling round her finger. You can temporarily see that the phone wire disappears when Marge puts it down. It is at the very end of an early scene, because as soon as this happens it changes to another scene. (00:04:40)
The Simpsons Christmas Special: Simpsons Roasting on an Open Fire - S1-E1
Audio problem: When Homer is putting Christmas lights around the outside of the house, he falls from the roof. You can then hear Lisa and Bart sarcastically clap. But you can see they both have their hands by their side, and no-one is clapping. (00:04:55)
The Simpsons Christmas Special: Simpsons Roasting on an Open Fire - S1-E1
Continuity mistake: During the family's breakfast, in most shots Marge sits right beside Maggie's highchair, but in certain close-ups they are quite a few feet away from one another. (00:05:25)
The Simpsons Christmas Special: Simpsons Roasting on an Open Fire - S1-E1
Continuity mistake: When Marge reveals the Christmas money from her hair, her necklace changes from red to white. (00:05:30)
The Simpsons Christmas Special: Simpsons Roasting on an Open Fire - S1-E1
Continuity mistake: While having breakfast, all of the Simpsons' glasses of orange juice keep disappearing and reappearing throughout the scene. (00:05:35)
The Simpsons Christmas Special: Simpsons Roasting on an Open Fire - S1-E1
Continuity mistake: When Mr. Burns comes on the P.A. system Homer started eating a donut, he takes a bite and after that the donut stays the same size even though he takes 2 more bites. (00:06:40)