Once Satanico Pandemonium ends her show, there is a close up
of Seth clapping his hands and saying "Now that's what I call a fucking show!" But in the next shot which is further away he is seen clapping his hands and mouthing the same thing again but no audio.
Jacob Fuller is established as a (lapsed) Baptist minister early on. At the scene behind the bar in the weapon room, he blesses water and makes the sign of the cross. A Baptist minister would never do this, as genuflections and the concept of "holy water" are Catholic.
After the brothers rob the liquor store, we see them driving down the highway and Richie's leg is hanging out the window. Seen from inside the car, his leg is inside and then he does not put his leg out the window until later.
Seth Gecko's tattoos change between scenes. From when they are in the hotel, to when they are in the RV, there is a change in design. At first two parts of the tattoo are attached, in the RV, they are no longer attached.
At the motel when Richie is bending to pick up the keys after dropping them, Kate has polish on her toes, but a short while later in the RV when Rickie is staring at her she does not have polish on her toes.
In the scene outside the Titty Twister, Seth grabs Cheech Marin's hand with his right hand, bending it back and to the side. In the next scene, Seth now has the same hold but applied with his left hand as he hits Cheech in the face with his right hand.
Before telling his story about Vietnam, Frost lights a match to light is cigar, despite the fact that a few scenes earlier he threw his match box on the ground to set one of the vampires ablaze in a puddle of liquor.
After they cross the border, Seth gives Jacob very simple instructions: drive straight forward until he meets a crossing road, then turn left. After they do they're driving towards a setting sun, however going south and turning left would have them face east, not west.
When Seth and Richie are in the Fuller's hotel room holding Scott and Jacob at gunpoint, Kate opens the door and stops when Richie and Seth point their guns at her, Richie then closes the door with her behind it but in the next shot of the door she is front of it.
During the fight in the Titty Twister, when the vampire's head rolls over towards Kate she actually misses the head when she tries to step on it. But in the next shot, it's sitting neatly under her foot.
The goof items below may give away important plot points.
Kate's crossbow starts with three arrows on each side and one in the middle. She fires numerous arrows at the vampires, yet her supply of arrows never seems to go down. For the most part, this is due to the fact that it is a pump-action crossbow (as is shown when she first cocks it after picking it up) that brings a new bolt into position when the string is cocked back with the pump. While this explains why she doesn't have to sit around and reload the thing after every shot, the six bolts attached to the bow of the weapon do disappear suddenly, and apparently without being loaded into the bolt cartridge.