Filmed on the same sets used for the Welsh mining village in How Green Was My Valley (1941).
"The Screen Guild Theater" broadcast a 30 minute radio adaptation of the movie on August 30, 1943 with Cedric Hardwicke reprising his film role.
The German occupation of Norway began with the invasion on April 9, 1940, and lasted to the end of the war in May, 1945. The size of the occupation force was immense--upward of 300,000 troops, or the equivalent of about 20 army divisions, enough for one soldier for every seven to eight Norwegian citizens.
The tune the German army is shown playing repeatedly, "We're Sailing Against England" was a Nazi "approved war song" for German soldiers in WWII according to the June 10, 194, issue of "Time" magazine. It was composed by Herms Niel (1888-1954) and had lyrics by poet Hermann Löns (1866-1914), who was killed in WWI. Originally a German Navy song from WWI, it became popular during WWII.