Other mistake: When Mr. Burns is talking to Apu, Doctor Hibbert and Chief Wiggum about supplying Springfield with power, he is writing with his right hand despite being left handed. (00:45:00)
Continuity mistake: When Homer is riding the motorbike around the ball of death, the first try he has the bike does not have flames painted on but after the third try the flames have appeared on the bike again. (00:41:30)
Continuity mistake: When Homer returns to Springfield, there is full security around the Dome. However, when the bomb explodes there is no sign of any security whatsoever. (01:00:00 - 01:10:25)
Continuity mistake: When Marge and Homer are watching the news about the silo being found, the '6' on Kent Brockman's microphone keeps getting smaller, the color of his belt buckle changes and the landscape in the background changes. (00:32:00)
Continuity mistake: The lead singer of Green Day disappears in the shot from behind the drummer's back - he is nowhere to be seen, even though where he was standing before means he should be visible from that angle. (00:03:20)
Continuity mistake: When Homer tries to convince Bart to come with him on the motorbike, he first holds the bomb in his right hand, but then it's in his left one in a different angle.
Continuity mistake: When the spaceship is landing, there are no craters near, but when Scratchy gets out, there are some craters there. (00:00:31)
Continuity mistake: When Mayor Quimby asks Cletus to demonstrate the anti-pollution barriers around the lake are idiot-proof, his entourage is spread apart, but the next shot of Quimby shows his entourage bunched closer together behind him.
Continuity mistake: When Homer and Bart are trying to outrun the crack in the dome, they are falling towards the damaged "P" in the Springfield sign. From their view, the top of the "P" is level with the letters "S" and "R" but when they use the bent leg of the "P" as a ramp to relaunch themselves at the dome, the top of the "P" is scrunched down almost halfway down from the other letters.
Continuity mistake: When the dome is lowered it is done so by 100s of helicopters that release the dome as Homer runs outside. The camera zooms out to show the whole dome and the helicopters have disappeared instantly. (00:26:20)
Continuity mistake: While Marge and Homer are watching the news on TV note their bed's footboard, then when Lisa angrily rushes into her parents' bedroom to confront Homer, the footboard's style is entirely different, but when Marge pulls Lisa away from Homer the footboard changes back to the original style.
Continuity mistake: When naked Bart skateboards past Wiggum's squad car, the vehicle does not have a partition screen between the front and back seats, a rear-view mirror, or a side mount searchlight, but in the following shots all have suddenly appeared, with other changes.
Continuity mistake: During the church scene, Martha Quimby is wearing an outfit with sleeves, but soon she's sleeveless, then back to sleeves, and finally sleeveless again. Behind Martha sits Bernice Hibbert, whose pearls also disappear and reappear.
Continuity mistake: Throughout the movie, the exterior side wall of the Simpsons garage changes length significantly, even between shots.
Continuity mistake: In the wide overhead shots as the crowd starts gathering at the dome edge and when Russ Cargill's image appears, note the homes on the third block at the far left side of the screen, which change when Cargill says, "Believe me it's the last thing we wanted to do."
Continuity mistake: When the Simpsons enter church they walk past Dr. Hibbert and he's wearing a solid black tie, but when Grampa has the outburst Dr. Hibbert is wearing a striped red tie. (Also, the stripes at the tie's knot are the same direction as the tie blade, though when tying the knot the stripes would be going the opposite direction).
Continuity mistake: In the first interior shot of the church, there are nine rows of pews on each side of the aisle, with Mr. Burns in the last pew on one side and Mrs. Glick in the last pew on the other side, but when Grampa starts rolling around on the floor there are eleven rows of pews, with two extra pews on both sides behind Burns and Glick. Additionally, the Reverend's wife is seated in the first pew, but just as Grampa shouts, "Trapped forever," we can see the back of an extra pew in front of Helen. (The front of the raised pulpit has vertical wood panels, and the pew is solid).
Continuity mistake: At church, seated in the pew behind the Simpsons are Moe and Kirk, and in the pew behind Moe and Kirk are Disco Stu, Professor Frink, and six other people, but just as Grampa shouts, "Trapped forever," in this one shot that entire pew with Disco Stu, the Professor, and all the other people has vanished, but then the pew reappears.
Continuity mistake: While Bart watches from the tree, Homer brushes the pig's hair and carries the animal out of the room, then Bart turns to see Ned tucking his kids in bed, and when Bart turns toward Homer again the lower window has a center muntin bar, but when Bart aims his slingshot at Homer that muntin bar has vanished.
Continuity mistake: When the silo is pulled out of the lake, Eddie is writing in a notepad. However as the silo turns round he has his arms crossed. (00:30:50)
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