When Esslin is bitten by Khorda, at one point we see the two bloody fang marks on the left side of her neck. It the next scene where she is dancing and later goes after Pico, the fang marks are gone.
When Barbado is driving his truck with the coffin through the town, the film is reversed and Barbado appears to be driving on the right side of the truck. A few scenes later, the film is correct and he's driving on the left side of the truck.
The vampire hippies carry Rona down the spiral stairs to the sound of them chanting a black mass to the devil. However, not a single person's mouth is moving throughout the scene.
When the surfer dude opens Khorda's coffin on the beach, it's broad daylight. It's later established that Khorda cannot walk around in sunlight. Why then wasn't he hurt when his coffin was opened?
Pico demonstrates his expert Kung Fu during his fight with Monk, but seems to forget this in the rest of the film and never uses it when attacked by the vampires.
Like most traditional vampires Khorda is repelled by the sight of the cross, and is upset by Monk's Iron Cross necklace, which he tells him to take off. Monk never does, and is still wearing it later when Khorda attacks and kills him. How exactly Khorda overcomes Monk's protection is never explained.