In 2025 Sony Pictures had recently announced an untitled Underworld movie would be in development in 2026, according to sources the film will most likely be a reboot of the franchise,
Peter Andersson's character is called "Vidar", which is the modern Swedish form of the Old Norse god "Vithar". In Norse mythology, Vithar is the son of Odin and destined to kill the monstrous wolf Fenrir at Ragnarök. The naming is therefore an obvious allusion to Vidar's role in the film as an enemy of the lycans.
All 4 rigging electricians credited are named Martin.
Kate Beckinsale stated in an interview that the idea of female Lycans came from director Anna Foerster and joked the reason why there had never been female Lycans in the prior films was because "other directors were scared that 'they might be ugly'."
While previous entries in the series had a distinctly eastern European flavor to them, this film has Scandinavian touches with a Nordic vampire coven and characters with names like "Marius", "Lena" and "Vidar" which are very popular in Norway and Sweden.