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)
Continuity mistake: In a scene Milhouse comes out of a house there is nothing in the yard, a long time passes, nearly ten minutes, Nelson comes over and there is a large rock in the yard. (00:09:40)
Continuity mistake: When coming down the dome the height of Homer on the dome changes between shots. (01:10:35)
Continuity mistake: Green Day's monitor speakers disappear from the stage depending on the shot. Most noticeable when sinking. (00:03:45)
Continuity mistake: When Abe goes nuts in church, Comic Book Guy gets his phone to record him. When it cuts to Abe, Comic Book Guy is not holding his cellphone. However when the family roll Abe out of the church, Comic Book Guy is holding his phone again. (00:05:20)
Other mistake: When Homer thinks he's out of the dome, he has a reflection, but Marge doesn't. (00:30:20)
Continuity mistake: When Homer shows up in the car as Bart is cuffed to the sign post, by the time Homer gives Bart the clothing the car moves up and back, and then when Homer kneels in front of Bart the car's back end is not visible, though it should be. (00:13:20)
Continuity mistake: When Lisa is meeting with Colin her clipboard disappears in some shots. (00:09:55)
Continuity mistake: When Homer is grooming Spider Pig he is in Bart's room and it's on the end of the house because you can see the corner of the house, then he walks out of the room and goes in another room but that room is on the end of the house too, you can tell it's a different room by looking in the background so it doesn't make sense that both rooms are in the same place. (00:15:45)
Continuity mistake: When the Simpsons see the nooses in their backyard, you see Jimbo and Kearney put a pacifier on Maggie's noose, but in the next shot where you can see the nooses, the pacifier is gone. (00:34:15)
Continuity mistake: When Homer is try to escape in the quicksand, his eyes are below the sand line. The camera cuts to Moe then back, and now his eyes are visible again. (00:35:35)
Continuity mistake: At the start, people in the church switch places instantly. Most noticeable is Chief Wiggum who moves from behind Ned on the left, to a few rows behind Marge on the right. (00:04:20 - 00:05:05)
Other mistake: For the car to be carried by the angry Springfieldians, there would need to be a big jump between the ground and the car, but from the car view there is no sign of that. (00:34:00)
Continuity mistake: A wood appears outside the Simpsons' fence when the dome has been lowered. (00:28:00)
Continuity mistake: When President Schwarzenegger tells Russ Cargill he will have to go back to making family movies, there is a "Diaper Genie" promo poster on the Oval Office wall and on the immediate left of President Schwarzenegger's desk. But the promo poster disappears and the walls of the Oval Office become further from the desk in the next long shots.
Other mistake: Homer puts superglue on his hands and gets his hand stuck to his groin. He then uses his second hand with superglue on to get his hand off but that hand doesn't get stuck. (01:04:10)
Continuity mistake: When Homer is dressed as General Marriot Suites he's wearing white gloves but after he punches the guard the gloves have vanished. (01:03:30)
Other mistake: Near the end of the movie Bart and Homer are on the roof. Homer hammers the nail into the roof then stands and the shingles are nailed to his leg, however, you can see that he did not nail it to his leg. (01:14:00)
Answer: The family doesn't treat him very well, particularly Homer. He may have wanted some revenge on them. Grampa is also a little senile.
Phaneron ★