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.

The animated opening was a compromise solution, since the studios had no interest in going over budget for a live-action version of the centuries-long battle of humans against vampires, so the scene was done by animation which was much cheaper to realize.

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).

Stephen Moyer did this film between seasons of playing a vampire in True Blood (2008).

This is Paul Bettany's fourth time playing a religious character. He played a monk in The Da Vinci Code (2006), the Archangel Michael in Legion (2010), a priest in The Reckoning (2002), and a priest in this movie.

The two companies responsible for building the bikes, Cinema Vehicle Services and Ghostlight Industries started with the Suzuki Gladius The builders took the initial artists sketches and made adjustments that would allow them to create fully functioning, usable vehicles for on the set of the film. The most striking thing about the concept bikes (apart from the huge turbines at the front) are their extended length and the low ride height which both pose significant challenges. Alloy swing arms were fitted to the rear of the bikes with a strengthened suspension setup similar to that used on sidecars. The front wheels were also extended out from the bikes using completely custom designed front ends. The low stance was then achieved by building custom fuel tanks that could be relocated to beneath the seat in the extra space created by the massively extended swing arm. Once the builders were satisfied that the chassis of the motorcycles were visually correct and safe to ride work began on the bodywork. Using foam and wood the extreme styling from the concept sketches was shaped over the heavily modified Gladius. Casts were then taken and fiberglass panels were produced for each of the six motorcycles built for the film. The final touches including paint, age effects and the weapons were then added by the productions art department before filming began. All the motorcycles produced for the film too around 6 weeks to produce. The priority of all the work done on the Suzuki's was their functionality and one builder was quoted as confidently saying that the motorcycles could be road registered and ridden daily. Some of the motorcycles still remain after filming had ended and are fully functional,

Gerard Butler and Steven Strait were originally cast.

Tentative plans for any sequel were quickly abandoned when the film flopped at the box office.

Cam Gigandet played James, a vampire, in Twilight (2008).

Director Scott Stewart originally wanted Brad Dourif's character to appear as a human/vampire-hybrid in the second half of the movie. Unfortunately, Dourif was only available for two days of shooting, so Stewart 'had to kill him off'