Continuity mistake: When Sheriff Rosco enters the bar and the Duke boys stand in front of him, in the shot from behind Bo loosens the strap of the helmet he is wearing but does not unclip it. In the next shot it is suddenly unclipped and loose, and he then removes the helmet. (00:15:50)
Continuity mistake: As Roscoe is trying to get Sheev's attention, the gummy worms in the pots, on the counter, change colour and position. (00:31:10)
Continuity mistake: The arrangement of the core samples in the safe changes, just after Sheev walks away. The two samples in the bottom left move to being in the centre. (00:36:50)
Continuity mistake: As Boss Hogg rolls backwards over his desk as Uncle Jesse punches him; watch the items on the desk as he lands on the floor. In the next shot the items are in different positions and some items are different. (00:49:40)
Continuity mistake: When Luke and Uncle Jesse are in Boss Hoggs' car, in the racing scene towards the end of the movie, Jesse is just about to start lighting and throwing the jars of moonshine. Just before he does, when he takes a drink from one his right hand is holding the cap on his head and the jar is in his left, but in the next shot the jar is in his right hand and the cap is in the left.
Continuity mistake: When the Duke's are in General Lee on the highway, people pass in their vehicles and shout at them. In some shots Bo has his hands on the steering wheel and in some shots they aren't. (00:40:35)
Continuity mistake: When Luke is showing Katie the core sample in the dormitory hallway, when she hands it back to him he puts it in his bag, but in the next shot it is back out in his right hand. (00:48:20)
Continuity mistake: The plastic explosives molded onto the safe that the Duke's and Sheev are going to blow open keeps moving (note the strips in the center of the safe door.) (00:34:35)
Continuity mistake: When the campus policeman is talking to Bo through his car window, the policeman has his hands resting on the windowframe. From every shot change, the policeman's left hand constantly disappears then reappears from the frame. (00:50:35)
Continuity mistake: Sheev's inner patterned jacket (under his orange bomber-jacket) changes position a few times from opened to closed, when standing around the safe. (00:34:00)
Continuity mistake: When Bo is talking to Billy Prickett in the bar, Dil walks up behind Billy and rests his hands on his shoulders. In the next shot he has vanished and then is suddenly back again, with his arms back on Billy's shoulders.
Answer: It was never mentioned on the show but the producer/writer has stated they died in a car crash in public and on the DVD.