Continuity mistake: After picking up Marlowe, the deputy with them mentions the car following them. They're out in the wide open area, but the car in the mirror is in the downtown area. Then after a quick cut, they're in the downtown area of Springville again.
Continuity mistake: The boys already had dynamite arrows made up. When they go to stop Marlowe's car, Luke says "Twenty-five percent charge ought to do it." They weren't carrying any extra dynamite, and weren't carrying the bags that held the bows where they would have had the extra charges.
Factual error: While the boys are chasing Marlowe in town after he takes Price's gun, he fires at them. He fires eight shots out of a six shooter without reloading. Also, Luke puts an arrow into the car to stop Marlowe, and steam comes out. But the arrow is too far back to have hit the radiator, and it only went in about an inch, far too high to have even touched the radiator.
Continuity mistake: The road that the Dukes are travelling on was clear about two minutes before, and the thugs were right behind them. After turning around to go the right way, they find the area they just came through blocked by a semi. No way the truck could have been set there that fast.
Continuity mistake: When the thug's car lands, you see it hit the ground in the distance shot. Then in the close up from the car mounted camera, you see it hit again.
Visible crew/equipment: As the Marlowe's men swerve to miss the ambulance, it goes airborne. As it does, you can see the camera mounted on the right side of the car.
Revealing mistake: When the boys are stopping to check the ambulance, you can see the smoke device burning used to simulate the engine running badly.
Continuity mistake: During the chase with the blue car, Price's hat goes on and off several times.
Continuity mistake: While running from the blue car, the area behind the Sheriff's car is an open area with a tan truck behind them. After the cut to watch the cars turn, the background area changes to the town, and the tan truck is gone. Also, Springville has all dirt roads, but during the chase, they run off the dirt and you can see the roads and buildings of Hazzard.
Answer: Various reasons, but mainly to drive the Dukes out of Hazzard County because the family have been foiling his schemes since his and Uncle Jesse's bootlegging days.
Captain Defenestrator