Factual error: In the opening scene, the Clampetts are driving home from Malibu. From Malibu to Beverly Hills is east. But as they head home, the ocean is on their left, which means they are driving west.
Continuity mistake: Granny is chasing after Jethro with the intention of paddling him. She runs into the mansion and her blouse changes color from blue to pink (or is it white?) and back to blue again in the same scene.