'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.
Jeff Chandler was originally offered the role that went to Cary Grant. Grant himself was at first reluctant to take it, knowing he was much too old to play a wartime captain.
Bob Hope always said it was his biggest regret that he turned down this movie.
Tina Louise was offered but turned down the role of Nurse Crandall that then went to Joan O'Brien because Louise didn't like the abundant boob jokes directed at the character.
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."
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."
Nurse Barbara (Dina Merrill), the love interest for Tony Curtis' character, was played in the 1977 remake by Curtis' daughter, Jamie Lee Curtis.
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.
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 only toilet was a one- or two-holer that was perched out over the bow - the "head of the ship."