From 1983 to 1984, director Jonas Åkerlund was a rehearsal drummer for the Swedish metal band Bathory, which was one of the inspirations for the Norwegian Black Metal bands of the 1990's which are focused on in this movie. He stated in a 2018 interview that when Black Metal culture developed in the 90's and become "too serious", he left the music scene and moved on to film-making.
Varg Vikernes has claimed that he was portrayed as a "power-hungry lunatic" in this movie, and that this is a deliberate misrepresentation based in part on the cultural misunderstanding of his passion for role-playing games in the 90's. Taking on fantastical personal titles and playing war-games with fictional factions on world atlases has become a normal part of culture now, but was noted as a suspicious form of power-fantasy by police investigators in the 1990's.
Director Jonas Åkerlund has stated in a 2018 interview that he used little black metal music in the movie in part because "it's kind of painful to listen to black metal music if you're not used to it or don't love it."
The trivia items below may give away important plot points.
Varg Vikernes stated in a 2016 video that Mayhem, Burzum, and Darkthrone all denied this movie rights to their music. However, since then it has transpired that the movie does in fact contain some of Mayhem's songs and (according to an interview with Jonas Åkerlund, the director) "the key players" are on board with the film.
Varg Vikernes has claimed that he never had a vest with band patches, never liked Scorpions, never drank chocolate milk at any point from 1991 to 1994, never punched a guy at a bar, never joked about putting all the death metal bands in gas chambers, never has "degenerate sex", and never was a vegan. But it is true that he was a non-drinker.