Anton Walbrook had aspirations as a classical pianist in real life and his hands are shown playing the piano. However, the piano part as heard was recorded by an uncredited Louis Kentner.
According to modern sources, the air-battle scenes were filmed during actual combat. Supermarine Spitfires of the No. 74 Squadron, RAF are seen.
Although this was a British RKO production, RKO leased it to Republic Pictures for release in the United States, while RKO distributed it in England.
Elwyn Brook-Jones's debut.