Blooper

After Gisla and Inga went to bed, Inga sneaks out to release Inge from the dungeon. When Gisla runs after her and stops her, he is (albeit in a hurry, and just out of bed) fully and properly dressed.

The film portrays Gisle / Håkon Galen as Bagler while in reality he was part of the Birkebeiner party.

The Norwegian coat of arms (a golden lion wearing a crown and holding an axe) appears throughout the movie, which takes place in and around 1204. However, the coat of arms did not exist in this form until approximately 1280.

In the film, Håkon Håkonsson appears while his father is still alive. In real life, he was not born until 2 or 3 months after his father, King Håkon Sverresson, died.

Potatoes didn't exist in Norway before 1750.

Norweigan, Danish and Swedish are presented distinct languages, but in reality the languages had not developed into separate languages yet. Norweigans would have spoken a west Norse accent, while Danes and Swedes would have spoken varieties of east Norse. Essentially the difference would be more akin to American English and Brittish English.

Norwegian, Danish and Swedish are presented as distinct languages but in the early 1200's, Scandinavians still spoke Old Norse. Through the language had split into distinct western and eastern dialects, the difference would be more akin to Australian English and American English than completely different languages.