The film was shot entirely on location. The main location; the bunker, is actually the ruins of the home the arch-bishop of Bergen in Norway from the 1200s. Today a church, "Nykirken", is built on top of the ruins.
Director Kjell Hammerø and cinematographer Bjørn Bøthun are also teachers at a two-year film school in Bergen, Norway; "Noroff School of technology and digital media". They recruited many of their former students to work on the film.
Sigurd Aae Klausen, who plays the films antagonist Konrad in Entombed (2020), studied acting in Drama Center London with classmates Tom Hardy and Michael Fassbender.