Continuity mistake: In the opening scene, the pages change in the magazine that the convenience store clerk is reading.
Continuity mistake: Throughout the entire film the tattoo on George Clooney's neck moves position and changes shape.
Revealing mistake: When George Clooney is talking to Juliette Lewis towards the end of the film, it is painfully obvious that his tattoo has been smudged.
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: 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.
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: At one point the RV is going down a rough, bumpy road and inside Seth and Richie are talking and everything is perfectly still.
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: Right after Salma's dance, Chet, the bartender and another big guy walk up to Seth and Richie and accuse them of kicking him and breaking Chet's nose earlier. One of Chet's men then stabs Richie's hand as Seth pulls out his revolver and shoots one of the other men. It is obvious and easy to tell that the bullets supposedly hitting the men aren't causing any kind of blood or damage, etc. In fact, it almost seems they are blanks.
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.
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.
Revealing mistake: In the scene where Kate is aiming her gun at Scott while he is being seized by several vampires, it is clearly a dummy surrounded by other dummies when the shot is made and the group explodes.
Revealing mistake: Shortly after passing the border Seth is talking to Jacob who's supposed to be driving. But the reflection in his glasses shows that they don't move.
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.