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.
Although many viewers thought the Japanese bomber pilot "Washing Machine Charlie" was fictitious, he did in fact exist, and is mentioned in William Manchester's memoir of the Pacific War, "Goodbye Darkness". He was also mentioned on 'McHale's Navy (1962 TV series)'
The real Greg 'Pappy' Boyington appeared in the second half of the two-part episode "The Deadliest Enemy of All" in the cameo role of Gen. Harrison Kenlay. He also appeared at the end of the first season's final episode "The Fastest Gun" as an officer who pins a medal on Boyington in newsreel footage.
As, at the time, there were no genuine A6M "Zero" fighters in flyable condition (this has been rectified only in recent years), all of the Japanese Zeroes depicted were actually American AT-6 "Texan" trainer aircraft that were specially modified to resemble a Zero.
When nurses were added to the regular cast, they were referred to in the opening credits as "Pappy Lambs" as a takeoff on the show that was beating this one in the ratings at the time, Charlie's Angels (1976).
Some scenes show the pilots holding the triggers for extended periods of time. Standard practice was to fire in 3-5 second bursts because the Corsair only carried enough ammunition for just under 30 continuous seconds of firing. There were 400 rounds per gun in the inner two guns and 375 rounds for the outer gun.