Continuity mistake: When Homer and Bart are on the motorcycle trying to get rid of the bomb, the bomb slips out of Bart's grip. When he's hanging onto his father's shirt, Bart first grips the bomb's handle with his palm and fingers facing the front of the bomb, with the clock. Then when he's hanging onto his father's hair, Bart's hand has flipped around and he's now gripping the bomb's handle with his palm and fingers facing the back of the bomb. Something to look out for is the shot just before the close-up of Chief Wiggum, because as Bart raises his arm the bomb actually flips over in his hand while we're watching. Quite impossible. (01:12:55)
Continuity mistake: Remy is reunited with his father in Paris. They are in a conversation at a little table. Remy's 'cup' moves closer to the edge of the table, towards our left, in several shots.
Other mistake: When Leela is signing the petition, Amy grows a third arm for a split second.
Continuity mistake: The live news broadcast of Superman's interview after his resurrection shows it broad daylight in Metropolis. When Martha Kent sees this at her farm, although being in the same state, it is pitch black night time outside at her house. (00:40:10)
Revealing mistake: Near the end, right when "little wonders" starts, Lewis takes a moment to look at his future family, Lucille, Frannie, etc. When there's a closeup on Lewis, his memory scanner reveals a reflection of no one in the gym, except for Lewis, even though people are supposed to be standing in front of him.
Revealing mistake: When the Level 3 Sentry is firing up into the air for no apparent reason, it fires some rockets with a clear defined smoke trail behind them and disappear off screen. Then the shot jump cuts to further away and suddenly the smoke appears again, but the end of the smoke trails are solid and crisp indicating the animators used the smoke animation as if the rockets had just been fired from that spot... in the middle of the sky. (00:01:10)