For the role, Nicolas Cage learned horseback riding from Camilla Naprous and her team of horse trainers in England. Cage also worked with a fight choreographer to learn sword fighting.
Nicolas Cage was attracted to the project because he saw it as a tribute to the movies of Roger Corman from the 1960s, which invariably starred the likes of Sir Christopher Lee and Vincent Price. It was a real bonus for him to discover that Lee was to appear in this movie too.
Filming took place in Austria, Hungary and Croatia. Most of the principal photography took place in practical locations, with several days committed to filming on green screen. Principal photography was completed by April 2009, but the cast and crew re-gathered a few months later to film additional battle sequences, filming on green screen to save on travel. The re-shoots were directed by Brett Ratner.
Wormwood, the name of the forest where blood is shed, is also the name of a destructive entity in the Bible. This entity, a star whose name also translates as Bitterness, appears to cause widespread illness. According to Revelation 8:10-11, "The third angel sounded his trumpet, and a great star, blazing like a torch, fell from the sky on a third of the rivers and on the springs of water--the name of the star is Wormwood. A third of the waters turned bitter, and many people died from the waters that had become bitter."