Revealing mistake: Bo and Luke Duke's car the "general Lee" usually has no glass in the side windows due the doors being welded shut as per NASCAR regulations which is why they climb through the windows to enter and leave the car, but when the general is doing one of its many jumps, in the long shots there is glass in the side windows.
Audio problem: Any time that the cars are squealing tires, there is an appropriate sound. However, every time they are sliding in dirt, there is the same sound. Unless there is asphalt or concrete under the dirt, there couldn't be any squealing sound.
Continuity mistake: The General Lee is a souped up Dodge Charger, often called a "stock car". As such, it has roll bars mounted inside. Every so often, you see no roll bars in it, meaning that there was more than one General Lee used in the series.
Revealing mistake: In the driver closeup shots, look at the backgrounds. A lot of the time, it shows the vehicle making turns, and the driver doesn't match the motion. Also, there are a lot of closeups where you see blue screen instead of scenery, or they go from city to country in a moment.
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