James Cagney's first film in Technicolor.
Many scenes were filmed at the Chateau Laurier hotel in Ottawa, Ontario. The hotel, which still exists, was originally commissioned by Grand Trunk Railway chairman Melvin Hayes. Melvin Hayes and most of the new furniture for the Chateau Laurier were lost in the Titanic sinking which delayed the hotel opening in 1912 by several months.
The film opened simultaneously in New York, London, Ottawa, Cairo, Melbourne, Toronto, Winnipeg and Vancouver. The R.C.A.F. transported film copies to these cities.
The German fighter shown attacking the bomber group is a Hawker Hurricane in Luftwaffe markings.
The graduation scene was an actual graduation ceremony of the R.C.A.F. with W.A. Bishop in attendance. He also attended the New York opening along with 200 R.C.A.F. cadets and other officials.
The training facility depicted in the movie, "Uplands Air Base," actually exists near Ottawa, Canada. After WWII, it served as a jet squadron training base and later as a military helicopter transport facility. In 1995, the Canadian government shut down the base and it now serves as a reception area for VIPs.
This was the first Hollywood picture to be filmed entirely on location in Canada.