The "sinking" of a truck was inspired by real incident that happened in 1944. On August 9th, USS Bowfin (SS-287) followed four ships into Minami Daito Harbour. As she fired her six bow torpedoes at the moored ships, hitting three and sinking two of them, one torpedo went astray and hit a pier. A bus parked on it was blown up and thrown into the water by the explosion.
Some of the plot points of the movie were based on real-life incidents. Most notable were scenes set at the opening of WW II, based on the actual sinking of the submarine USS Sealion (SS-195), sunk at the pier at Cavite Navy Yard, the Philippines; Cmdr. Sherman's letter to the supply department on the inexplicable lack of toilet paper, based on an actual letter to the supply department of Mare Island Naval Shipyard by Lt. Cmdr. James Wiggin Coe of the submarine Skipjack (SS-184); and the need to paint a submarine pink, due to the lack of enough red lead or white lead undercoat paint.
The nurses wonder why the toilet is called "the head." It's because on earlier sailing ships, the toilet for enlisted sailors was a series of holes, like an outhouse, that was perched out over the bow - the "head of the ship." This location was for practical reasons as the wind was always blowing from the aft; therefore, any "offensive odors" were blown away from ship. The officer's toilets were near the stern or back of the ship within the "quarter gallery", the part of the stern that hung over the water on either side.
'USS Balao' SS-285 was painted pink and was used for exterior shots in and around Key West. 'USS Archerfish' SS-311 (originally 'USS Archer-Fish', renamed at 1952 recommission) wore the standard colors of gray and black, and was used for interior and exterior shots in and around Key West. 'USS Queenfish' SS-393 was used in opening and closing scenes, and was used for the "at sea" shots filmed in and around San Diego.
According to the memoir "Mislaid in Hollywood' by Joe Hyams, referred to in the biography "Cary Grant - A Class Apart" by Graham McCann, " . . . Grant found his burgeoning enthusiasm for his therapeutic use of LSD increasingly hard to contain, and, eventually, while he was shooting the movie "Operation Petticoat", he could hold back no longer. Two reporters - Joe Hyams and Lionel Crane - both prepared for the usual amusing but scrupulously bland Grant interview, were stunned to find him unusually relaxed, open and keen to share with them the extraordinary experiences he had undergone . . . He talked about his desperate desire to change his character so that he could be reunited with Betsy Drake."
A submarine based at Cavite, the USS Seadragon, did go on patrol with a red paint job. Her original black paint was damaged by fire in the air raid, and ended up peeling off while she was on patrol. She ended up sinking three Japanese ships during the time her paint was peeling, leading Tokyo Rose to make broadcasts about "Red pirate submarines."
Of the three boats to portray the 'Sea Tiger', one-the 'USS Archer-Fish', SS-311-was present at the Japanese surrender which ended WWII in the Pacific Theater. The 'USS Wren', DD-568, which was shown as the destroyer attacking 'Sea Tiger', was also present.