Continuity mistake: When "Emperor" Moe appears in front of Marge, after she and the kids return, the two cartridge belts swung over Moe's shoulders switch from his left over the right, to his right over the left. (01:04:50)
Continuity mistake: When a naked Bart is cuffed to the sign post, beyond the grass behind him is concrete walkway then the curb. Then when Homer steps out of the car, the grass goes right up to the curb's edge, but when Bart asks about pants, the walkway is back again between the grass and curb. (00:13:05)
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: When Maggie does her disappearing act through the sinkhole, and Marge rushes to get Homer, the wooden porch swing is directly in front of the window, with its top beam as high as the top of the window. When Homer says, "This dome can play tricks on you," note the door and window behind Marge, because the swing is now gone. (00:31:10)
Continuity mistake: The second time Russ Cargill spreads out the five options on the President's desk, the name bar with 'President Schwarzenegger' on it vanishes and reappears on the desk twice. The spread of the files also inverts between shots. (00:50:40)
Continuity mistake: During Homer's attempt at rescuing his family, when the EPA truck stops at the fake stop sign in the wideshot the truck's visors are up and there's no rearview mirror, but in the next closeup both visors are down and a rearview mirror has appeared.
Continuity mistake: When Chief Wiggum orders his men to open fire on the dome, and the bullets ricochet back, the officer standing farthest from Wiggum is wearing blue gloves on both hands in the overhead side shot, and the other officers are not wearing gloves. However, in the shot facing them, the officer kneeling farthest from Wiggum is the one wearing blue gloves, and now all the others are barehanded. (00:28:35)
Continuity mistake: When Bart is having target practice on Homer, who is carrying bricks, the timer lying on the grass goes off. When Homer walks over to Bart to give him the dare, the timer is gone, though it should be visible. (00:11:20)
Continuity mistake: When Lenny calls Homer about free doughnuts Hans Moleman is in the background (in Lenny's scene) then Homer drives to the lake to dump the pig crap silo and he runs over Hans Moleman, but he was at the doughnut shop so he couldn't have gotten to the lake in time. (00:22:30)
Continuity mistake: When Homer heads to the lake to dump the silo, the car's rearview mirror disappears and reappears. (00:23:50)
Continuity mistake: The Simpsons leave the dome with nothing. However when Marge, Bart and Lisa are on the train and in the EPA van, Lisa has now got her sax. (00:37:05 - 01:00:15)
Continuity mistake: When Homer drives to the lake to dump the pig crap silo, there are hundreds of 'No Dumping' signs along the way, but on the way back, all the signs are gone, including the ones Homer missed. (00:22:55 - 00:23:40)
Continuity mistake: When Marge runs back to the kitchen to retrieve the wedding video, the house is ablaze. In the next shot, when the mob is carrying the car away, there are no flames visible in the house. (00:33:40)
Continuity mistake: In front of Krusty Burger, when Lou carries a naked Bart to the sign post, the post is embedded directly in the concrete walkway slab, just beside the left corner of the patch of grass. Once Bart is cuffed, the sign post has actually moved down about 4 feet, and is also now embedded directly in the grass at the right corner. In following shots, it's at the left corner of the grass and then right again. (00:12:50)
Continuity mistake: There is no circular window on the church from the outside but on the inside there is. (00:06:50)
Continuity mistake: We see the interior of Homer's car twice, first when Homer is at the Hazardous Waste Treatment Center, and then again when he and Marge are trying to escape the angry mob. The dashboard and steering column are entirely different both times. (00:23:20 - 00:35:20)
Continuity mistake: When the mob is charging toward the Simpson's house, we see Nelson in his regular clothes. When he shoots the arrow at the Simpson's, he is wearing a Springfield T-shirt. (00:33:15)
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