Continuity mistake: When Bo pulls General Lee up outside the University, it is parked at an angle from the curb. After they leave the university and return to the car it is parked much more straight. (00:51:05 - 00:55:45)
Continuity mistake: After Bo has brought Billy Prickett a pint of beer, the beer glass keeps moving as evident by the handle changing its direction. Also the pint is completely full, but when Bo picks it up to drink from it (before attacking Dil) it is half full. (00:12:45)
Continuity mistake: After the boys run five miles to the Boar's Nest, the sweat stains on Bo's blue t-shirt starts disappearing and reappearing. When Bo gives a beer to Billy Prickett, his shirt is dry in one shot, and then again has a wet sweat stain in the next. The shirt goes through other various stages of sweatiness throughout the Boar's Nest scene. (00:09:30)
Continuity mistake: The distance between Sheev, Bo and Luke as they stand in front of the safe waiting for it to explode, and again when Luke shoots the arrow at it, keeps changing. (00:35:20)
Visible crew/equipment: After the Dukes have had their talk with Prickett, and get back in General Lee to go get Uncle Jesse, the shot stays on Prickett for a moment. If you watch in the grill of his truck, you can see the crew and a boom mike reflected in it. (01:13:10)
Continuity mistake: In the courthouse scene, the judge's name plaque is on his left side, but seconds later it is to his right with there being no time for him to move it across. (01:33:35)
Continuity mistake: During the car chase through the fields with Bo being chased by the police, the sky keeps changing from light blue to very dark blue, to even a light orange in some shots. (01:15:25)
Continuity mistake: After the black soot splurts all over Bo and Luke, the amount on their shirts and faces differs through the scene. (00:54:20)
Continuity mistake: When Bo is talking to Laurie's father (while Laurie and Luke are in the upstairs bedroom) you see Laurie throw some clothes out onto the roof. In the very next shot the clothes are in different places. (00:04:05)
Visible crew/equipment: When Bo and Luke are talking to the geology student, and Katy Johnson pops in the door to hurry them up, just after she dances for Luke in the doorway, the camera pans back to Bo and Luke. Just then, a boom mic pops into frame at the top of the screen, then quickly moves back out. (00:55:00)
Continuity mistake: Towards the beginning, after Bow and Luke make there delivery to Laurie. Bow and Luke run away from Mr. Pullman(Laurie's Pa) and the brother. The son fires a shotgun at the Dukes from the right side of the truck and when he hits Mr. Pullman with gun, he fires, but the hole ends up on the left side of the car. Which is impossible with the angle he was shooting from.
Continuity mistake: During the rally race, Bo is driving down the forest lane and before catching up with Billy Prickett, he passes a green rally car - twice. Also, after he passes it the second time, it vanishes from the road completely. (01:28:30)
Continuity mistake: When we hear a gunshot and Luke rolls out of the upstairs window onto the roof, the whole upper house is bathed in sunlight, then is instantly in complete shade. (00:04:15)
Continuity mistake: When Luke and Bo are being chased in the beginning of the movie, a huge bullet hole is made in the left side of General Lee. Moments later it has vanished.
Continuity mistake: When the police cars pull up outside Cooters, just as the Duke's drive out with the fixed General Lee, the position of the police cars keep changing (note it's position in relation with the parking markings.) (00:37:25)
Continuity mistake: The rally race reporter has a microphone with a label around it sporting the channel logo. However moments later in the courthouse scene, the channel logo on the microphone he holds is completely different. (01:30:10)
Revealing mistake: When Bo lands General Lee on the highway after going up the ramp, in one frontal shot you can see the front left wheel of the car come apart completely and break its suspension. But the car is unaffected and continues to drive. (01:07:45)
Continuity mistake: When Billy Prickett walks into the back garage to find Sheriff Rosco and Boss Hogg, there is a car beisde them with a white sheet over it. During shots, the large creases in this white sheet keep changing. (00:42:30)
Continuity mistake: After the opening car chase, when General Lee is trapped between two vehicles, Bo hoists himself out the window, then Luke does the same after. But in the next exterior shot, they both are hoisting themselves out at the same time.
Visible crew/equipment: Whenever Luke wears his sunglasses, but most noticeably in the opening car chase, stage lights are reflected in them.
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.