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 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: After the book knocks over the AA meeting's coffee machine, when the group of people run out of the church, the ground in front of its doors is flat and leads straight to the walkway. Additionally, there is a second large area of grass between the sidewalk and the street, and the large cross at the front is gone. However, in previous and following shots there are stairs at the front of the church, and the area of grass only between the church and sidewalk/street.
Continuity mistake: With the second set of options spread across the desk, when Cargill starts manipulating the President's option choice, there is a blank wall to the President's left (the wall faces the viewers). Also note that in this shot the table behind the President (with framed photos) is gone. When Cargill walks away from the President holding 'option 4', that blank wall now has a built-in bookcase, a table and chair.
Continuity mistake: There is a blue Presidential flag behind the President, with windows on both sides of that blue flag, but after viewing the security camera footage of domed Springfield, the window on the far end has become a solid wall. That window returns when Cargill influences the President's choice of options.
Continuity mistake: When Russ Cargill spreads the second set of the five options across the President's desk, the Oval Office background is actually backwards - note the ship painting over the fireplace and pictures on the wall. The background keeps flipping between being backwards and the correct way until 'option 4' is chosen.
Continuity mistake: After Russ Cargill goes through the eye security system, in the overhead shot as he enters the Oval Office, we see the Seal of the President (on the rug) centered between the two couches, and there are two red chairs behind each of the couches. However, when Cargill holds up the tank with the mutated squirrel, the large round Seal is off to the side of the couches and one of the chairs is gone from behind the couch. (00:24:50)
Continuity mistake: When Russ Cargill holds up the tank with the mutated squirrel to the eye security system on the wall, there is a square piece under the handle to secure it to the top. However, when Cargill holds the tank up to the President that square has vanished and it's just the handle. Then when the President is face-to-face with it, a bar has appeared between the two sides of the handle. (00:24:50)
Continuity mistake: When Lou shoots at the skateboard Bart goes flying in the air, and in the next shot (before he flies past the truck's windshield) we see Krusty Burger across the street (note the triple window and post), and there is a tall, long bush between the street and Krusty Burger. That bush vanishes in the following shots. (00:12:50)
Continuity mistake: When Lou scrapes Bart off Krusty Burger's triple window, Lou is pushing Bart forward in front of him, so Bart should have fallen on the ground somewhere to the front/side of Lou. However, in the next shot Bart is lying on the ground about 20-30 ft behind where Lou had been standing, on the grass that's in front of the door. (00:12:55)
Continuity mistake: When Lisa goes door-to-door with the petition, the door on Milhouse's house has two grooved panels, a tall, 12-panel window, a light fixture above the door, and there's a tree between it and the blue house next door. When Lisa sees Colin and Milhouse again near the end, some of the features of the house have changed - unrelated to the damage Springfield's homes have suffered. The door now has three grooved panels and no mail slot, the window is much shorter, and the light fixture above the door is gone, with no hole in the wall if it had been broken off. The tree between the house and the blue house next door has changed position on the grass as well. (00:09:10)
Continuity mistake: When Nelson punches Milhouse in the stomach, there is a hose hanging below the window attached to a spigot, and the front door has two grooved panels on it, but when the dome approaches and Milhouse swallows his inhaler, the door is flat and smooth, and the hose, its holder and spigot have vanished and been replaced with a bush.
Continuity mistake: When Lisa is going door-to-door with the petition, Milhouse opens his front door and there is no mail slot on the door, but when Nelson punches Milhouse in the stomach there's a mail slot on the door, beside the door knob. (00:09:10)
Continuity mistake: When Bart falls off the roof and grabs hold of the gutter, in the overhead shot the gutter is an L-shape with a 90° angle, but after Homer and Bart high-five each other, the gutter is a straight line that ends at the corner. (00:08:10)
Continuity mistake: When Cargill confronts Homer, he raises his shotgun. In the next shot, his shotgun is suddenly lowered. (01:11:35)
Continuity mistake: When everyone is saying "Lord hear our prayer" at the church, Kirk van Houten is wearing a blue suit, but later when Grandpa is freaking out, Kirk is wearing a red suit. (00:04:05 - 00:05:40)
Continuity mistake: When Homer dumps the silo in the lake, there are the words "Pig Crap" on the front and there is no writing on the back. However, when Lou and Eddie find the silo later in the movie, the "Pig Crap" words are there, but the words saying "Return To Homer Simpson, No Reward" has appeared out of nowhere. (00:23:00 - 00:30:50)
Continuity mistake: When Homer leaves the bar Eski-Moes (in Alaska), he catches hold of a truck, which propels him up the hill in front of his cabin. However, he runs outside a few minutes later and floats away on the heart-shaped iceberg, which has suddenly appeared on a lake that was never there before. The road that the truck was on earlier is gone.
Continuity mistake: The Simpsons enter a motel (Red Rash Inn) to hide, and it's clear from the outside that the building is only one story high. But when Homer flings back the curtains to reveal the buildings and billboards, it appears that the motel room is located on a much higher floor, since the view seems to be level with the building tops.
Continuity mistake: In the scene where they are climbing the rope to escape the dome, the hole seems to be very wide. Yet when Homer is on top of the dome the hole is very small.
Answer: I believe the joke is supposed to be that the way Texans speak is a language all its own.
Damian Torres