Continuity mistake: In the final battle, Jacob turns into a vampire and bites Scott, when Scott hits Jacob with the holy water bomb, Jacob backs away from Scott, when Jacob removes his mouth from Scott's neck, there is no blood on it, two cuts later, there is blood on Scott's neck.
Continuity mistake: When Jacob gets bitten, he is thrown across the room by Sex Machine. If you look closely as he's flying through the air, you can see the wound on his arm has disappeared.
Continuity mistake: During Santanico Pandemonium's routine, two dancers take the snake away so she can step forward. As they take the snake off, the second dancer is holding only a couple feet of the snake's tail, but in the next shot, the second dancer is holding the entire snake. (00:55:40)
Continuity mistake: When Sex Machine turns into a vampire, he covers his mouth so he doesn't show his fangs. When his hand changes, he tries to cover it up with his other hand. Watch this other hand. In the shot where THAT hand changes, it is in a different position from before. (01:21:35)
Continuity mistake: In the shot where we see the bar (for the very first time) they are going to, you can see the background is flat, kind of like the building is on a flat area of land with nothing behind it. At the end of the film we see not only a giant ditch but also the trucks from over the years piled up behind the bar.
Continuity mistake: During the scene when Seth questions why the bartender will not serve him, several camera shots go to the band on stage You don't even have to watch carefully to know the band, especially the drummer, are not playing their instruments and/or their miming is way off.
Continuity mistake: In the hotel when the manager comes through the door, in the first shot the door is open, but the next time the door is closed.
Continuity mistake: Frost gets green blood all over his hand after holding the vampires heart, but this disappears while they are fighting the four women. After the fight finishes, the blood returns.
Continuity mistake: At one point the RV is going down a rough, bumpy road and inside Seth and Richie are talking and everything is perfectly still. (00:42:30)
Plot hole: When Seth's piledriver gives out during the climactic fight, there are many vampires in the background politely keeping their distance while he tries to restart it. Similarly, they ignore him while both his hands are occupied with Sex Machine's whip, even though vampires are running around behind him to no apparent goal. (01:31:35)
Continuity mistake: After Seth and Richie capture the Fullers, Seth sends Richie outside to start the car. Richie picks up the keys, stands up facing Kate, then exits past her to the right. As the door closes, she is standing against the wall - he would have walked to the left to pass her. (00:29:00)
Continuity mistake: When Frost drops the first of 4 vampire waitresses/dancers onto the legs of an upturned table, he drops her belly first but she lands on her back. There doesn't appear to be enough time for her to turn over in mid air and land perfectly on her back.
Continuity mistake: When it shows a shot from the front of Seth, Kate and Scott running from the bats, some bats catch up with them and fly past them. But in the next shot from the back of them, no bats have flown past.