Karl Urban gets to give a severe thrashing to Brad Dourif in this movie, after having been prevented from doing so by another character in The Lord of the Rings: The Two Towers (2002).
The girl Priest is looking for is called Lucy. This is a throwback to the Dracula of Bram Stoker, where there is also a character named Lucy, who is also an engaged redheaded girl in need of saving.
At the start of the final battle between Priest and Black Hat, Black Hat kicks Priest into a vent on top of the train car. During subsequent long shots of the train and some shots of the length of the train there are no vents visible anywhere along the top of the train.
In many scenes, the cross on Priest's face, which is supposed to be a tattoo, is wiped off from the end of his nose and reappears as a full cross. One of the most noticeable moments in a short time span is at the Nightshade Reservation. Priest has one of the familiars pinned to the ground and when the camera focuses on his face, the end of the cross has been wiped off. Camera switches back to the familiar who points to the sky and when Priest turns to face the sun, the cross is fully drawn on again.
After stabbing and strangling Priest, Black Hat tosses a lit lantern at Priest's feet starting a fire directly below Priest so he will burn, some of the flames hitting Priest's shoes. However, when Priest later regains consciousness all of the flames are in a semi-circle several feet away from Priest with no burn marks anywhere near his feet.
Hicks: [after Priest explained that Hicks should anticipate a vampire's move, he had to learn how to see their movement from Point A to Point B. And Hicks was apparently learning because he just, finally, shot a vampire]
Point A? Meet point fucking B.
What are the differences between the Theatrical Version and the Unrated Version?
A
Designed for a low rating (no nudity, one F-bomb), the action scenes in Priest were pretty close to an R-Rating . To assure the PG-13, some minor modifications of the images and the audio needed to be made, just like the MPAA demanded. In a couple of scenes, the CG blood has been reduced and colored differently. Furthermore, some obvious noises during the process of stabbing or some bones that get broken have been removed from the audio track. The fact that brutal stabbing itself is fine with the MPAA, as long as is doesn't SOUND that gruesome, made the director wonder. A detailed comparison between both versions with pictures can be found here.