When Eric Toresen (Paul Muni) left his daughter at Mrs. Olav's house and went into the mountains, he left behind the jacket he arrived with. Later after coming back down from the mountain, and without returning to Mrs. Olav's place, he has his jacket on again.
At the meeting to discuss whether to resist the German invasion a female attendee says, ''Let the British win the war, let the Americans win the war''. The Germans invaded Norway in late Spring 1940, America didn't enter the war until December 1941.
During the firing squad scene, the second soldier from the left fails to correctly load the bullet into the chamber. On closing the rifle bolt, the bullet is seen hanging out of the chamber, and then drops to the ground.
Poor throwers: when the English are attacking the aerodrome, thrown grenades explode roughly two to five meters from where they actually land.