Continuity mistake: When the dome is being placed over the town, the church and Moe's Bar are shown right next to each other, but later on in the film, when Barney runs out of the Alcoholics Anonymous meeting at the church, Moe's Bar is nowhere to be seen. (00:26:30 - 00:48:30)
Continuity mistake: When Russ Cargill spreads the five unthinkable options on the President's desk, the book's spines are all facing to the left, but after the President chooses option three, in the close-up the spines are facing to the right. (00:26:40)
Continuity mistake: When the dome is placed over the town and Marge says "Trapped forever, it's all coming true" we can see a hose on the garden tap in the background. But a couple shots previously we could only see the garden tap but no hose. (00:27:10)
Continuity mistake: After the dome is placed, when the Simpson family runs out the back door of the house and Homer shouts, there is only one window on the second floor, above the back door. There should be two windows. The light fixture on the wall beside the door is also gone in some shots. (00:27:40)
Continuity mistake: When everyone approaches the edge of the dome, a group of police officers arrive. As Chief Wiggum says "open fire", he is standing in front of the officers. In the next shot, Wiggum and the officers are standing even with each other. (00:27:40)
Continuity mistake: A wood appears outside the Simpsons' fence when the dome has been lowered. (00:28:00)
Continuity mistake: When the dome is lowered we see Sideshow Mel hitting it with his bone. In the background you can see Dr. Hibbert and his wife. When Russ comes on the dome, Dr Hibbert and his wife are now in a completely different spot, and have changed sides. (00:28:00)
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 Maggie gets out the dome, Marge runs to get Homer. They run outside in a straight 12 o'clock direction. Yet as Homer says "This dome can play tricks on you", they are suddenly several steps to the right of the door instead of being directly behind it. (00:30:00)
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 Marge sits on the back porch swing knitting 'dome sweet dome' and sees Maggie outside the dome, she runs inside to get Homer. The back door is right behind her and it's a solid door, with the round window missing, though the window does reappear. (00:30:35)
Continuity mistake: When Marge and Homer are watching the news about the silo found in the lake, the TV sits on the dresser in front of their bed. The TV has vanished when Lisa runs into the bedroom, and when Marge tells Homer to go out, face the mob and apologize for what he did, the rest of the wall is visible, sans TV. (00:30:40)
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: After Marge has brought Homer to see Maggie outside the dome, and then he thinks he's out of the dome, when he runs back into the house the water spigot attached to the house has vanished. (00:30:50)
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)
Continuity mistake: When Marge brings Homer to see Maggie outside the dome, but she's not there, he soon starts cheering and in the dome's reflection he raises his right arm which means it's his left arm that is actually raised, but when it cuts to Marge and Homer (in the view from outside the dome) it's his right arm that's raised in a cheer. (00:31:05)
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: After Homer taunts the angry mob about not knowing where he lives, the mob gathers in front of his house, and in the shot of Homer and Marge in the bedroom note the light switch on the wall and the items on the dressing table, but in the next shot as Lisa and Bart run into the room the items on the table have vanished and the light switch is gone. (00:31:30)
Character mistake: The mob is marching to Homer, however they are going the wrong way. In the mob we see several people who all know where Homer lives. So why march the other way? (00:31:40)
Continuity mistake: When Homer falls onto the barbecue during the failed escape, there is a lower window at the corner of his house, which didn't exist in the exterior shot of the house, just before we see Homer and Marge watching the news about the silo being discovered. (00:31:50 - 00:34:50)
