Factual error: The clothing and most noticeably the armour of the Viking warriors is a very higgledy piggledy collection of dress from different places and times in history. Only Buliwyf actually seems to be wearing armour of Viking origin, some of the others have Spanish Conquistador armour and helms from centuries after the film is set and another wears a Roman gladiator's helm complete with face mask, another of the group is seen to be wearing a kilt (the redhead conveniently played by one of the two Scottish actors used as Vikings)which may well have been worn concurrently by their celtic neighbours but his kilt is quite modern in design.
Factual error: The Vikings follow the Norse religion, and make several references to it throughout the movie. But when waiting for the first Wendol attack, Herger states "The All-Father wove the skein of your life a long time ago". In Norse mythology, the All-Father (Odin) did not weave the skein of life, the Norns did.