Continuity mistake: The chase with Daisy in Rosco's squad car ends with a piano slamming into the car. When the truck hauling it comes to a stop, there's a reaction shot of Daisy at the wheel of the squad car. In the next shot, when the piano hits it, the car is empty. A second later, Rosco gets out of the truck and Daisy is back in the driver's seat. (00:30:00)
Continuity mistake: As Bo and Luke pull up to the wrecked Sheriff's car, the roll bars are not in the General. As Bo climbs out, the bars are suddenly there.
Continuity mistake: In the opening scene, first the Sheriff's car, then the General land at a forty-five degree angle. You see the Sheriff's car looking like it has a definite bow downward in the middle. The General gets a compression dent over the front wheel well, but later it is smooth down the side.
Continuity mistake: After she first boots Rosco, Daisy is driving his car. The close up of her driving you see the right front corner of the truck Rosco commandeered to chase her behind her. Trouble was, that Rosco hadn't gotten the truck yet.
Continuity mistake: When the Sheriff's car approaches the construction area, you see there is no ramp anywhere, and the road area isn't bumpy enough to account for the car flipping and rolling.
Continuity mistake: When the Sheriff's car is being chased in the beginning, you can see that the driver is wearing a ball cap. At one point, you can see the hat the unknown driver wears turns to the hat worn by Rosco, as you can see the brim. Later, it's revealed that the unknown driver was Cooter.
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