Alexander Knox who plays the German Captain in 8th credited position, also provides the uncredited voice of the off-screen Chaplain of the British naval vessel, as well as that of the off-screen closing narrator.
A rejected score was composed by Igor Stravinsky. He published his unused music as "Four Norwegian Moods"
Behind-the-scenes footage made during location filming in Canada is included in the CBC-TV documentary "Canada's War in Colour" (2005).
Bristol Blenheim light bombers and Westland Lysander liason aircraft were painted up with German Balkankreuz markings to stand in for unavailable Luftwaffe types.
This film was one of a handful of movies that were all released around the same time that dealt with the Norwegian Resistance in World War II. The movies include They Raid by Night aka The Commandos Have Landed; Commandos Strike at Dawn; First Comes Courage and Edge of Darkness.
This was the movie debut of 43-year-old George Macready, who had been a stage actor since 1926.