Continuity mistake: During the town hall meeting, Mayor Quimby's podium has a recessed panel at the front which vanishes when he asks who's in favor of a new scissor lift platform. (00:19:50)
Continuity mistake: When Homer walks into the kitchen to show Marge his new Simpson addition, we can see the shelving unit under the window in the den that has a single spindle and finial from the top to middle shelf, with two blue books lying on their sides, but in the closeup of the pig's tail now there are two spindles and two finials, with a red book that's upright. (00:15:25)
Continuity mistake: When Homer brings his pet pig home to meet Marge, they enter the kitchen and the roll of paper towels is hanging under the cabinet near the window, but in the closeup when he and the pig share a carrot the paper towel roll and its holder have both vanished, and then they reappear. A cutting board suddenly appears on the counter as well. (00:15:30)
Continuity mistake: At the town hall meeting, when Lenny says, "It's not so bad," there's a single head light fixture on the wall near the balcony, but when Moe shouts, "This is why we should hate kids," there's a double head fixture on the wall, and yet in the first overhead shot of the meeting there's no fixture at all in that space. (00:20:05)
Continuity mistake: After Lou chains Bart to the pole with his cuffs, the next shot shows he has a new pair, when he didn't in the last shot. (00:12:20)
Continuity mistake: When Bart falls off the roof and grabs hold of the rain gutter, it's one continuous seamless piece of trough material, but in the following shots that gutter consists of a few connected sections. (00:08:05)
Continuity mistake: There's a tiled patio at the back of the house with a total of twelve large tiles, but when the house goes down the sinkhole there are sixteen tiles in total. Plus the fact that when Bart's on the roof hanging from the gutter the tiles below are white (they also appear white when the house falls into the sinkhole), but when the dome is placed over Springfield the tiles are brownish-orange.
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 Bart and Lisa are looking at the cabin from a hill, the cabin only has a shallow incline to the water, but in a later scene, when Homer goes to look for his family, there's a significant slope.
Answer: I believe the joke is supposed to be that the way Texans speak is a language all its own.
Damian Torres