This is the first film in history to feature Old Norse, the ancestor of Modern Icelandic and several other Scandinavian languages. Howard McCain used an Icelandic professor to help translate the dialogue and to teach the actors how to speak the ancient language.
The language spoken by Kainan and his computer in the beginning of the movie, is actually Icelandic as it was pronounced in the twelfth century. The dialogue between him and the computer is as follows: Kainan asks: "Staður" (=location). Computer responds: "Stadhur: Noreg, taeknistig: Jarnold" which means "Location: Norway, Technology: Iron age". Kainan asks: "Leita skips" (Vessel search). Computer responds: "Leita....engin skip fundust" which means "Searching - no ships found". Kainan says: "Senda merki" (which actually means "send signal" but is translated as "language"). Computer responds: "saeki talmal: norrænu" which means "Loading dialect: Norse". When Kainan has buried his friend he says: "Far vel, herra" which is subtitled as "Sleep well, sir" but more correct would be "Fare well, sir".
Sophia Myles' character is called Freya. In the Norse mythology, Freya was the goddess of fertility and beauty, but she was also a warrior goddess who would choose half the slain warriors to have in her hall, Sessrumnir. Odin would take the other half for his hall, Valhalla. Freya was not Odin's wife, that was Frigga.
Jack Huston (Wulfric) did all of his own stunts (as did the other actors) and broke his shoulder during the film: at one point, he rolls underneath the Moorwen and slashes it with his sword; he offered to do the scene without a mat, and when he hit the ground he immediately realized it was broken. However, he continued with the take and waited until "cut" was called to get medical attention. The scene occurs about seventy-nine minutes in, and he can be seen standing rigidly still in the next couple of shots after the stunt.
Originally the film was to be shot in New Zealand with a significantly higher budget. They already scouted New Zealand and Weta was going to do the effects. But the financing fell through and the production got delayed.
Two years earlier, Sophia Myles starred opposite David Tennant in Doctor Who: The Girl in The Fireplace (2006) as Madame De Pompadour. Five years after the film's release, Sir John Hurt starred opposite David Tennant in Doctor Who: The Day of the Doctor (2013) as The War Doctor. David Tennant was Sophia Myles' boyfriend from 2005 to 2007.