Character mistake: When Homer discovers that the Leftorium is going out of business, there is a sign that says 'Coming Soon: Gum for Less' beside the store. Later on, though, Ned says the new store is becoming 'Libertarian Party Headquarters.' (00:15:50 - 00:19:15)
Suggested correction: The sign is just an advertising poster that's on a wall. It's not in front of the leftorium.
The Simpsons Christmas Special: Simpsons Roasting on an Open Fire - S1-E1
Continuity mistake: Lewis changes from black to yellow when Milhouse dares Bart to pull Santa's beard off. (00:14:10)
Tree House of Horror X - S11-E4
[The Simpsons are driving down a road as fast as possible.]
Homer: Dear God, it's Homer. If you really love me you'll save my life now.
[The gas needle immediately drops to empty and the car stops.]
Homer: D'oh.
Trivia: The Simpsons holds the record for most guest stars; it is also the only non-variety show to have had appearances from three former Beatles (Paul, George and Ringo).
Question: Which episodes feature the "Howling Dog" (usually used on outside shots of buildings)?