Audio problem: When Maggie is trying to point out the sinkhole, Marge says "We'll play later." Her mouth doesn't match what she says.
Audio problem: When Homer is falling down the rope, his speech doesn't match up with what his mouth is saying.
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.
Audio problem: When Homer fails motorcycling around The Ball Of Death, the shot cuts to inside the Ball Of Death. About a second after the shot cuts inside The Ball Of Death, Homer is heard sighing. But his mouth doesn't move. A sigh like that would require his mouth to move. (00:41:40)
Audio problem: A little bit before Reverend Lovejoy says he's going to call on someone, the church organ is being played. But as the camera pans around to Lovejoy, we can see the woman is not touching the organ keys, but the sound is still heard. (00:04:45)
Answer: I believe the joke is supposed to be that the way Texans speak is a language all its own.
Damian Torres