Revealing mistake: After the crowd boos at Homer after kicking the bomb, Bart is shown walking past The Android's Dungeon and the shot pans over to show Comic Book Guy. Just as the shot begins to pan over, it can be seen that Comic Book Guy randomly pops up on screen.
Continuity mistake: The shot where Homer kicks the bomb shows a group of people a few meters behind him. A few shots later, they are suddenly right behind him.
Audio problem: When Homer is falling down the rope, his speech doesn't match up with what his mouth is saying.
Continuity mistake: When Cletus goes to distract Cargill, a crowd of Springfield citizens go to place the KBBL news tower next to the rope so they can climb up it. They are all on the ground when Cletus starts talking to him. Cletus then says "Look what I can do with my thumb" and the crowd is suddenly half way up the rope with no time to do so.
Continuity mistake: When Homer squirts the super glue on his hand, he throws the glue container on the floor behind him. When he starts to climb up the wall, the glue's container has vanished from the ground.
Revealing mistake: After Homer knocks out the guard guarding the dome, Homer runs into the supplies shack. As he walks through the doorway, his right arm passes through it.
Continuity mistake: After the title card "Immediately" is shown, Homer is lying unconscious in the snow. Next to Homer's hood is an extra amount of snow rest next to his ear. Next shot, the extra snow has vanished.
Continuity mistake: When Homer puts the video in the VCR player, as Marge says "Homer", outside the window shows a dark sky in the background. Marge then talks for a bit and the shot returns to Homer saying "Way back." Outside the window suddenly shows a background that is partially brighter and raining.
Audio problem: When Marge, Bart, Lisa and Maggie are trying to convince Homer to save Springfield, after Homer says "That is the stupidest thing I ever heard", Marge says "Homer Simpson!" then Lisa says "We're saving Springfield." When Lisa says "Springfield", her mouth reads something totally different.
Continuity mistake: After the Alcoholics Anonymous meeting runs out of the church, Barney starts yelling and a huge crowd is visible behind him. Bumblebee Man is standing a few meters away from Barney on the end of a row. Next shot, Otto and Moe have suddenly appeared next to him as well as a huge crowd.
Continuity mistake: When the Alcoholics Anonymous run out of the church, Barney yells out "I can't take another minute in this dome!" and charges towards the dome. In the overview shot, the church is directly behind Barney. In the following shot that shows Barney hitting the dome, the background has changed completely. The church is no longer there and two houses have suddenly appeared.
Continuity mistake: When the two deer enter through the cabin window to help Homer and Marge, a trail of snow is visible behind them and in front of the window. In an instant close-up of the smaller deer, half of the snow has instantly melted and vanished. Then all the water has vanished and it's just snow. Then a few shots later, the snow vanishes completely.
Continuity mistake: When Marge and Bart are at the counter at the gas station, the first shot of them at the counter shows the strap on Marge's bag facing behind the bag. The shot then changes to Bart using his slingshot, and Marge, visible in frame throughout the entire shot, is never shown touching the bag, but when the shot cuts again, the strap is suddenly in front of the bag.
Continuity mistake: When the Simpsons are at the gas station, Marge congratulates Bart on being sober for 24 hours. The Buzz Cola can next to Bart has the logo facing front ways. Bart then aims his slingshot which cuts to a shot from behind them and the Buzz Cola logo on the can is still facing front ways, despite the angle change.
Continuity mistake: When the mob are invading, Lisa sees Colin in the crowd with a bouquet of flowers and nothing else. Later on after the house is destroyed, he suddenly has a guitar with him despite not having it with him a few minutes earlier. (00:32:30)
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)
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: When Bart and Ned find the mutated squirrel, two EPA workers find the creature. When the female worker says "Environmental Protection Agency" after Ned asks who they are, the squirrel is standing on a rock with nothing under it. In the next shot, there is suddenly something under it for the EPA worker to contain it with. (00:24:30)
Continuity mistake: When Marge asks Homer about Spider-Pig "What are you doing with his leavings?" Spider-Pig is looking straight forward at the TV. In the next shot, Spider-Pig is suddenly looking at Homer. (00:21:30)
Continuity mistake: After Homer decides to bring Spider-Pig home with him, the scene cuts to Maggie playing the game Baby Blast. On the back of the game console is the cartridge with the words Baby Blast written on it. As Grandpa says "I'm pretty sure a thousand is a number" a few seconds later, the words Baby Blast have vanished from the cartridge. (00:15:00)
Answer: I believe the joke is supposed to be that the way Texans speak is a language all its own.
Damian Torres