Three languages are spoken in the film. The Birkebeiner speak Norwegian, the Baglers speak Danish, and Queen Margrete speaks Swedish. This is actually an anachronism as the Nordic languages had not split into completely different languages at the time and the characters would have spoken more or less the same language, albeit with heavy accents.
One of the publicity stills from the movie, which is shown on the back of the disc case and in the disc menu, is a recreation of the famous painting "Birkebeinerne på Ski over Fjeldet med Kongsbarnet" by Knud Bergslien. This painting is now housed in the Holmenkollen Ski Museum in Oslo, and shows the two rescuers on skis; one is holding an axe in one hand and cradling the infant in the other arm, and the other rescuer is holding a spear with both hands.
Three Norwegian medieval kings appear in the film. Håkon III Sverresson, Inge II Bårdsson & Håkon IV Håkonsson.
The character "Gisle" is based on the real life Norwegian Jarl "Håkon the Crazy". The name was changed to avoid confusion in a movie that already have two Håkons. Jarl Håkon was also never directly antagonistic towards his brother, Inge, even though they are said to have had a shaky relationship at best.
Professors at the University of Oslo criticized the film's historical inaccuracies on the university's history website.