Continuity mistake: The vampire who gets tossed into the grinder mysteriously reappears in the final showdown. You see him twice while the head vampire is fighting with Eben.
Revealing mistake: Watch closely in the Gus murder scene, as the vampires start surrounding him outside in the snow, notice the very first vampire "close-up" shriek, remember the face. After Marlow and Iris attack the couple in their house he puts his claw to the record player and emits a howl as the other vampires throughout the town follow suit with their own shriek, each one gets his/her own close-up, count to the fifth vampire face and you will notice it is the exact same shot used earlier in Gus's murder.
Revealing mistake: In the scene Josh Hartnet's character dumps the vampire into the grinder, and gets beat up by the one who turned into a vampire, in the close-up shot of his face where he is bleeding, look at his nose. The patch make up used for supposed ripped flesh is visible. It's colored orange and is rather obvious.