This film represents one of four movies made by Hollywood during the 1940s that were about or related to the US military's Dolittle Raid on Tokyo, Japan, during World War II. The four (the first three considered "fictionalized") are Destination Tokyo (1943); The Purple Heart (1944); this film; and Thirty Seconds Over Tokyo (1944), the last being the most accurate and least fictionalized of the four.
The "American" bomb sight mentioned throughout the movie was the Norden bomb sight whose secret was almost as closely guarded as the development of the atomic bomb. It used a mechanical computer and linkage to the plane's autopilot to achieve an accuracy of hitting with 75 feet of the target from an altitude of 12000 feet. All members of the bomber's crew were ordered to destroy the sight at all costs if the plane was going to crash. Many ships carried a hand grenade to place under the sight to assure total destruction. It was used as late as 1967 to drop sensors along the Ho Chi Minh trail in Viet Nam.