Beowulf & Grendel
Hammer of Thor
Historical Setting: 500s CE
Important Note: Much like King Arthur, this won't be about dissecting the finer points of the legend of Beowulf and comparing it with the poem. This is about looking at what the movie presented to us as history and whether it was true or not.
Second Note: I'm actually kind of sad that I don't have much to complain about, historically, in this movie. It was such a bad movie and I'd hate to think that it helps prove the point that historically accurate movies are bad.
In the scene where the Danes are celebrating the opening of their mead hall, there was no feast. Religious ceremonies like this were always accompanied by food and drink.
The Celtic "priest" in the movie should have been called a Celtic monk. He was even dressed like a monk - or at least how movies dress monks. And, at the time, Ireland had a lot of monasteries and monks but priests really only came after the Famine when the population converted from Irish Catholicism to Roman Catholicism.
The conversion of the various groups of Vikings to Christianity didn't really pick up steam until somewhere in the 800s and 900s CE. Before then missionaries didn't have much luck in converting the people. In fact merchants had "better" luck, as some Vikings would agree to be baptized in order to do business, but still held on to their beliefs. Also, when some where trying to merge the two belief systems, or at least appear to be converted, they would wear their Hammer of Thor necklace so that it looked like a cross. Not like the Danish king wore it in this movie, post his baptism.
The Danish king would not be happy to hear that he would die in his bed. In the Viking afterlife the only good place to end up was Valhalla and you would have to die in battle for that to happen. People who died natural deaths ended up in Niflheim, a dark realm ruled by the goddess Hel, who would feast on their corpses.
Sources
Vikings: Raiders From the North. Virginia: Timelife, 1993. Pg 31.
Roberts, Morgan J. Norse Gods and Heroes. New York: Friedman Group, 1994. Pg 57.
Saxons: http://www.answers.com/Saxons
Sarmatians: http://www.answers.com/Sarmatians