Birgitte Hjort Sørensen and Nikolaj Coster-Waldau have both starred in Game of Thrones (2011) and 3 Things (2017).
Nikolaj Coster-Waldau's character was inspired by famous action heroes, Indiana Jones and John Rambo.
Steven Berkoff character's name, Jack Pudovski, was inspired by Lt. Col Podovsky from 1985 action movie Rambo: First Blood Part II (interestingly, also portrayed by Berkoff).
According to Nikolaj Coster-Waldau, the torture scene of Severin Geertsen was inspired by interrogation sequence from Rambo: First Blood Part II.