Although many viewers thought the Japanese bomber pilot "Washing Machine Charlie" was fictitious, he existed, and was mentioned in William Manchester's memoir of the Pacific War, "Goodbye Darkness". He was also mentioned on McHale's Navy (1962).
There is a famous photo of every member of the Black Sheep Squadron posing on the wings of one of their planes wearing St. Louis Cardinals baseball caps. The Cardinals donated one cap for every Japanese plane the squadron shot down. They ended up donating so many caps, that everybody in the entire squadron, including the ground personnel, got one.
Most of the aerial footage was shot off the Southern California coast. The island seen during the closing credits is (the eastern tip of) Santa Cruz Island, facing southeast.
Some scenes show the pilots holding the triggers for extended periods of time. Standard practice was to fire in three to five second bursts, because the Corsair only carried enough ammunition for just under thirty continuous seconds of firing. There were four hundred rounds per gun in the inner two guns and three hundred seventy-five rounds for the outer gun.
As shown in the pilot, Boyington was originally called "Gramps" by his men because he was a decade older than the men in his unit. A song written by one of his men changed it to "Pappy" which was then picked up by war correspondents and stuck.