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)
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)
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.
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)
Continuity mistake: During the Green Day concert, the lyric displaying teleprompter sits onstage beside the mic stand, but then disappears, reappears and disappears again by the time the barge sinks. (00:03:10)
Continuity mistake: At the end when everyone is congratulating Homer, Comic Book Guy is by Homer. Homer then rides down the street to Marge and Comic Book Guy is suddenly by Marge. (01:13:05)
Continuity mistake: When the family move to Alaska, the door to their cabin opens to the left (looking at it from the inside) when Homer escapes from Bart and Lisa's "avalanche". But later in the film it opens to the right (from the inside). (00:46:25 - 00:52:05)
Continuity mistake: In the scene where everyone is climbing the rope to get on the top of the dome, Homer should already be at the top, but when the camera points to the top of the dome, he does not appear there. The next scene shows him back at the top of the dome again. (01:05:15)
Continuity mistake: Eddie and Lou are at the lake making notes about the Pig Crap Silo. The next shot is of the town approaching the Simpson house and Eddie and Lou can be seen in the mob. (00:30:50)
Continuity mistake: When Homer circles the dome on the bike, in the first two shots (close-up and wideshot) Homer's left hand is gripping Bart's left wrist, but in all of the following shots it is Homer's right hand that is gripping Bart's left wrist. (01:12:50)
Continuity mistake: The clock on the bomb instantly jumps several seconds despite instant cuts. It goes 17, 16, *instant cut* 11, 10. (01:09:40)
Continuity mistake: The door to Homer's cabin in Alaska changes positions, from facing the street when he comes home from the bar to facing over a cliff when he decides to follow Marge and the kids back to Springfield. (00:46:25 - 00:52:45)
Answer: Homer has been known not to make the smartest decisions, and the decisions he does make, he makes without fully thinking them through. Clearly he wanted to get some donuts as quickly as possible without thinking of any other ways, so he decided to ditch the silo in the lake as it would be the fastest way of getting it off his back, even if it's not the smartest. Also, putting that aside, he likely wanted his own pick of the donuts rather than have Lenny guess what he wanted.
Casual Person