King Kristian is seen eating a stew with cucumber in it. But the movie takes place in 1520, and cucumber wasn't introduced in Scandinavia until 200 years later.
One of the main characters is called "Freja". "Freja" was only introduced as given name in the 19th century after the "viking revival" movement, derived from the Icelandic "Freyja". Names derived from the pre-christian deity of that name had mutated into "Frö-" due to sound developments in the Swedish language.
The main characters are two women with the surname "Eriksson". In the 16th century most of the population of Sweden, including nobility, used patronymic surnames. A person would have their father's name and the suffix "son" (son) if a man and "dotter" (daughter). The use of former patronymics as a family name only started to occur in the late 18th century and only became widespread in the 19th.
Promotional images shows Sten Sture carrying 10th century viking sword, which would be an antique in the movie's 16th century setting.