The Flying Tigers' planes were full-size mock-ups made mostly of plywood and balsa wood, not - as has often been thought - real aircraft. The "engine" noises were sound effects added after production.
The opening scene shows a Japanese air raid and in the aftermath a crying child is sitting alone amid debris. This scene virtually duplicates a famous photo taken in 1937 and published in Life magazine following a Japanese air raid on Shanghai. (Located in the National Archives, ARC Identifier: 535557)
The "Tiger Shark" teeth and eyes painted on the noses of the planes were there for psychological reasons. It was believed that the Japanese, coming from a seafaring nation, would be frightened of being attacked by sharks. There is no word on whether it had any effect.
Some clips of the dogfights and Japanese ack-ack guns were from confiscated Japanese newsreels.