Continuity mistake: When circling the dome on the bike, it leaves tyre marks. The camera cuts to Bart and the marks have gone. (01:09:30)
Continuity mistake: When Bart is proving he is sober, Homer is pumping petrol and eating a hotdog. The camera cuts and Homer is eating a hotdog but not pumping petrol like he was a second before. (00:43:45)
Continuity mistake: At one point during Grandpa's outburst in church, Marge is shown standing up. In the next shot, she is suddenly sitting down. (00:05:55)
Continuity mistake: When jumping the gorge, the position of Homer and Bart changes depending on the angle. (01:10:50)
Continuity mistake: Milhouse is seen when Lisa is looking for Colin and a few frames later he is in the middle of the town with no time to move there. (01:13:40)
Continuity mistake: When Bart is talking to Ned about going fishing with Homer, he has a sling-shot that disappears throughout the scene. (00:06:15)
Continuity mistake: When Homer and Bart are fixing the roof (near the beginning) there is no tree near Ned Flander's house. Later on Bart is on a tree next to Ned's house talking to Ned Flanders.
Continuity mistake: The arrow that Nelson fires into Homer's head changes place between shots. It goes from on top to the side. (00:35:30)
Continuity mistake: When Grandpa is freaking out in church, he says, "twisted tail" while kneeling with his hands cupped, "a thousand eyes" leaning up against a pew, and "trapped forever" standing up and spinning. On Comic Book Guy's cell phone video he says all of these on the floor rolling around. He's also saying it faster on the cell phone video. (00:05:50 - 00:10:20)
Continuity mistake: At the end when Homer is nailing the two tiles to the roof, they are yellow. The camera cuts and now they are red. (01:14:00)
Continuity mistake: When Marge is reconstructing Grampa's prophecy with magnets on the fridge, she moves the magnet saying" eyes" up a few inches to complete a sentence. When the shot changes to a wider angle, the magnet is back where it was before she moved it. (00:14:45)
Continuity mistake: When Homer kicks over the bomb, Comic Book Guy is seen seen behind him, with Carl, Cletus, and Krusty. In the next shot, Comic Book Guy is gone (appearing a few shots later at his comic book shop), and Barney is there instead. (01:08:45)
Continuity mistake: When Bart skateboards to Krusty Burger naked, he passes Agnes Skinner in the middle of town. On the left side of the screen is Mr. Largo, the school music teacher. A few shots later, when Bart approaches KB, Mr. Largo is seen walking down the sidewalk. There is no way he could have caught up and passed Bart in that time span. Not only that, but he and Bart are headed in completely different directions. (00:12:05)
Continuity mistake: When Bart and Homer are up on the roof, Homer puts the hammer on the roof next to his leg. In the next shot when he dares Bart to climb the antenna, it's gone. (00:07:40)
Continuity mistake: The bottle of ink and quill on Mr. Burns' desk disappear for one shot. This happens when Apu, Chief Wiggum and Dr Hibbert are asking for some electricity. (00:46:05)
Continuity mistake: In the motel room after escaping the dome, the circles of light made by the lamps on the walls and ceiling change between shots. (00:40:00)
Continuity mistake: In the scene where the newscast (Day 37) is being watched on the TV at Moe's, in the first shot of the TV there is a dart in the roof, but in the long shot the dart is no longer in the roof. (00:43:40)
Continuity mistake: When Colin is trying to play "Lisa's song" from the other side of the glass, at first the guitar has an f-hole, and in the next shot of him, it's a solid body guitar. (00:36:25)
Continuity mistake: During Bart's flashback of him and Homer fishing, Homer drops the bug zapper into the lake. Dozens of fish come floating to the surface all over the lake. After the shot where Homer scoops up a fish and is zapped for it, there's a reverse-angle shot of Bart with no dead fish in the lake around him. (00:16:30)
Continuity mistake: When Homer is forced into the house by Bart and Lisa's avalanche, it is broad daylight, but seconds later he is with Marge in the bedroom and it is dark outside. It is not snow surrounding the house, because the animals come in through the windows. (00:48:30)
Answer: I believe the joke is supposed to be that the way Texans speak is a language all its own.
Damian Torres