Corrected entry: After the Inuit scares the polar bear away it kicks a fox. But the fox is orange when in that part of the world it should be white.
Corrected entry: During Lisa's survey of the lake, the crazy cat lady is cleaning her cats. But when she is doing this, it looks like there is an infinite amount of cats in the box that they are in.
Correction: That's the joke in the scene. As it is done deliberately, no mistake.
Corrected entry: When Bart falls off the motorbike, while riding up the inside of the dome with Homer, he has to grab onto Homer's hair to save himself from falling, and Homer starts to scream in pain. After a while, when Homer only has one strand of hair left for Bart to hold onto, Homer sounds like he stops screaming, but his mouth is still wide open and his tongue is still sticking out in the classic cartoon 'screaming' position.
Correction: Just because a person's mouth is open and tongue flailing doesn't mean they have to be screaming. It could easily be described as Homer's reaction to the pain of having his hair pulled out.
Corrected entry: A heavenly beam of light falls on the bike that Homer uses to ride up the dome, but the bike wasn't there in previous shots. (01:07:45)
Corrected entry: When Marge closes the curtain in the motel room the other curtain changes from being open and closed between shots. (00:38:15)
Corrected entry: Right after when Homer asks what the secret knock is, the lock changes from a rectangle with a circle, to a rectangle, back to a rectangle with a circle. (00:38:50)
Corrected entry: When the Simpson family are at the motel after getting out of the dome, Homer knocks on the door to ask what the secret knock is. The door opens without Homer opening it, and the rest of the family is nowhere within arm's length of the door to open it.
Correction: One of them strode forward, turned the knob, then, as the door was swinging open, strode back to wherever they were so they wouldn't have to greet or otherwise acknowledge him. Every hotel/motel I have stayed in had doors that swung open if the latch wasn't in place; it's so you're less likely to lock yourself out.
Corrected entry: When the dome is being lowered over the town one of the edges is near the right side of the schoolyard. Later (when Marge, Bart, Lisa, and Maggie get put in) the only edge near the school is in the back of the schoolyard (if there's an edge near the school at all).
Correction: Already listed and corrected. Many locations in Springfield change around, both within the series and the movie, all according to which jokes the makers want to insert in particular scenes.
Corrected entry: When Russ Cargill is on the big screen explaining why the EPA has put a dome over Springfield, you can see the Simpsons' house is next to the edge of the dome (Flanders' is on the other side) but later in the movie there's a row of houses on the other side of the Simpson's house.
Correction: Already submitted and corrected: the layout of Springfield, and the locations of various buildings changes constantly throughout the movie (and the TV show for that matter).
Corrected entry: Before Green Days' Funeral there is a Text board outside the Church. Later, when the dome is being lowered over the town and the people in the church run into Moe's and the people in Moe's run into the Church, the text board is gone.
Corrected entry: When Homer's "Pig Crap" silo is found a police man is writing a report on a notepad. The police man moves the notepad down, but the words on it stay where they are and they go through the police man's shirt.
Corrected entry: When comic book guy is showing Marge the video of Grampa freaking out in church, the video on his cell phone camera then moves to a different angle. This is impossible.
Correction: Many of the things that happen in this movie are impossible. Why single this one out?
Corrected entry: When the dome has been lowered there is a far out shot of Springfield surrounded by a forest yet throughout the tv show they are next to their rival town Shelbyville.
Correction: First, the movie is not the TV show, and the locations of different businesses etc are different as well. Since the movie is stand-alone, and the forest does not change in the movie, it's not a mistake. Second, in the TV show, locations change all the time, as evidenced by the nuclear plant being right next to the Simpson's in some episodes, and far away in others, it's part of the humour of the series. Finally, Shelbyville is close to Springfield in some episodes, and miles away in others as when Homer et al rescue Ned's motorhome in one episode, but in another episode, Homer sees road signs for Shelbyville being miles away while driving in other episodes.
Corrected entry: Bart pokes the 100-eyed squirrel in five of its eyes, but when it cuts to a wider shot the squirrel is squinting in pain with six of its eyes.
Correction: It's not unreasonable to think that the squirrel's mutation caused some occular nerves to combine.
Corrected entry: In the scene where Homer opens the poster of Alaska he opens it in hundreds of squares, during shots the size of the squares he unfolded it from changes multiple times.
Corrected entry: When Bart is hiking up the hill with Flanders, in the wide shot Flanders has a walking stick and Bart doesn't, but it then cuts to a closer shot and Bart suddenly has a stick.
Corrected entry: When Maggie, Lisa, Bart and Marge jump from the treehouse to the sandbox portal to escape the Springfield mob after them, no one of the mob sees the four jump in the sandbox despite that many were around the sandbox. They only notice Homer jump and get stuck initially. There would be no way for anyone to miss the other four Simpsons jump.
Correction: This isn't really a mistake - they probably did see them, but they're only after Homer, not the rest of the family.
Corrected entry: When Grandpa is freaking out in church, Milhouse's dad Kirk is sitting directly behind Homer. But when Homer is looking through the Bible to try and help Grandpa, there is no sign of Kirk at all. (00:05:45)
Correction: Due to the angle of the camera he will not be visible when Homer is flicking through the bible.
Correction: No, you're thinking of an Arctic fox, which is white, but there are also red foxes in Alaska as well. Both breeds of foxes live there, not just Arctic foxes.