Continuity mistake: During Bart's flashback of him and Homer fishing, Homer drops the bug zapper into the lake. Dozens of fish come floating to the surface all over the lake. After the shot where Homer scoops up a fish and is zapped for it, there's a reverse-angle shot of Bart with no dead fish in the lake around him. (00:16:30)
Continuity mistake: When Homer is forced into the house by Bart and Lisa's avalanche, it is broad daylight, but seconds later he is with Marge in the bedroom and it is dark outside. It is not snow surrounding the house, because the animals come in through the windows. (00:48:30)
Continuity mistake: The one eye by the back leg of the squirrel keeps disappearing and reappearing depending on the shot. (00:24:25)
Continuity mistake: When Nelson says "I'm using a red arrow so I know who I kill," the word "Springfield" appears on his sweatshirt. It wasn't in the previous shot. (00:34:40)
Continuity mistake: When Homer starts to replace the shingles on the roof there is a box of tiles, however, when Bart climbs the antenna, they have disappeared. (00:07:25)
Continuity mistake: When Homer cuts the ropes securing the Pig Crap Silo to the car, he leaves an axe mark on his car. In the next shot the mark is gone. (00:23:05)
Continuity mistake: After Grandpa goes nuts in the church, they go to the car. You can see that Homer has a seat belt on, but when Marge gets out he does not. (00:06:45)
Continuity mistake: After the mob knocks down the front door Krusty tells Teeny to, "Take out the baby," and when Maggie breaks her bottle to take on Teeny, the monkey is standing on the fallen door, but in the next closeup he's standing on the floor beside the door.
Continuity mistake: When Russ Cargill provides the President with the first set of five options and spreads them across the desk, the handle on the mutated squirrel tank is perpendicular to the president, but in the next shot the handle has flipped around and is now parallel to the president. (00:26:10)
Continuity mistake: The tattoo on Cletus' upper arm has vanished when he volunteers to distract Cargill so the others can attempt to escape, but the snake tattoo reappears when he's talking to Cargill.
Continuity mistake: When Marge looks at the magnetic words "a thousand eyes" on the fridge and asks Grampa about it, other than the highchair Maggie's sitting in, there are two chairs around the kitchen table - one Grampa's sitting on and one empty chair, but in the next shot as Homer introduces the newest Simpson there are now three chairs - Grampa's chair and two empties, the one beside Marge appeared out of nowhere. (00:14:50)
Continuity mistake: When Marge gets into the car and tucks the wedding video into her hair, the rearview mirror is attached to the roof of the car, but as the mob carries the car to the backyard the rearview mirror is now attached to the windshield.
Continuity mistake: When the angry mob breaks down the front door of the house, the door knob is on the right side of the fallen door, at Chief Wiggum's feet. However, when Maggie breaks her bottle and thrusts it forward, in the next shot as Mr. Teeny turns and runs away, the doorknob is on the left side of the door, at Bumblebee Man's feet. (00:32:20)
Continuity mistake: When Lisa sees Milhouse near the end, the door on his house hangs askew from the right door jamb and there is nothing above it. However, after Colin shows up, in the next shot when Lisa jumps up, the door now hangs askew from the left door jamb and there is wiring hanging above it (from the broken light fixture). Also note that the roof is much lower, and a spigot appears under the window. Additionally, Lisa's position when talking to Colin changes - first they're standing to the left of the house, then to the right of it, then in front of the stairs at the center.
Continuity mistake: When the dome is being lowered over Springfield, The amount of choppers carrying the dome changes depending on the shot. (00:26:20)
Continuity mistake: When the angry mob is outside the Simpsons' home, Lisa sees Colin in the crowd. Carl is next to him, with his torch in his left hand. In the next shot, when Carl sets fire to a bouquet Colin brought for Lisa, Carl's torch is now in his right hand. (00:33:55)
Continuity mistake: When Homer is climbing the dome, there is a shot of the rope. No-one is climbing it, yet a few seconds before people were climbing the rope. (01:05:10)
Suggested correction: They didn't climb high enough to be visible. Homer was much higher than they were.
Continuity mistake: The "Duff Beer" blimp disappears from the sky while "Green Day" are performing. (00:03:00)
Continuity mistake: When Bart is chained to the post, a large piece of grass used to cover him appears from nowhere. The post also changes places from the sidewalk to the grass. (00:08:15)
