This was the first Hollywood picture to be filmed entirely on location in Canada.
The German fighter shown attacking the bomber group is a Hawker Hurricane in Luftwaffe markings.
The air training school outdoor scenes were filmed at the Royal Canadian Air Force base Trenton, near Belleville, Ontario, where pilot trainees and staff served as extras in the film. The training aircraft used were North American Harvards, which were a Canadian version of the NA At-6 Texan trainer. The Silver trainers shown in flight, are North American NA-64 "Yale" trainers. They look very similar to the later North American AT-6 "Harvard", but have fixed landing gear with fairings, and the fuselage was fabric covered. 119 were delivered to the RCAF of which approximately 30 are still in existence.
MacLean's aircraft, CF-HGO in the scenes, was a Noorduyn Norseman, Johnny Dutton's silver CF-NBP was a Fairchild 71C bush plane, and the other float planes were a Waco EGC-7 and Waco AGC-8 cabin aircraft. The Noorduyn Norseman is in the Canadian Bush Pilot Museum located at Sault Ste. Marie, Ontario.