Years after the film's release, a movie reviewer asked Tony Curtis why his "Josephine" was so much more feminine than Jack Lemmon's "Daphne." Curtis explained he was so scared to be playing a woman (or a man pretending to be one) that his tightly wound body language could be read as demure and shy, traditionally feminine traits, whereas Lemmon, who was completely unbothered, and "ran out of his dressing room screaming like the Queen of the May," kept much more of his masculine body language.
Jack Lemmon wrote that the first sneak preview had a bad reaction with many audience walkouts. Many studio personnel and agents offered advice to Billy Wilder on what scenes to reshoot, add and cut. Lemmon asked Wilder what he was going to do. Wilder responded: "Why, nothing. This is a very funny movie and I believe in it just as it is. Maybe this is the wrong neighborhood in which to have shown it. At any rate, I don't panic over one preview. It's a hell of a movie." Wilder held the next preview in the Westwood section of Los Angeles, and the audience stood up and cheered.
Tony Curtis has said that he asked Billy Wilder if he could imitate Cary Grant for his stint as the millionaire in the movie. Wilder liked it and they shot it that way. Apparently, Grant saw the parody of himself and stated, jokingly, "I don't talk like that."
Marilyn Monroe wanted the movie to be shot in color (her contract stipulated that all her films were to be in color), but Billy Wilder convinced her to let it be shot in black and white when costume tests revealed that the makeup that Tony Curtis and Jack Lemmon wore gave their faces a green tinge.
Marilyn Monroe required 47 takes to get "It's me, Sugar" correct, instead saying either "Sugar, it's me" or "It's Sugar, me." After take 30, Billy Wilder had the line written on a blackboard. Another scene required Monroe to rummage through some drawers and say "Where's the bourbon?" After 40 takes of her saying "Where's the whiskey?", "Where's the bottle?", or "Where's the bonbon?", Wilder pasted the correct line in one of the drawers. After Monroe became confused about which drawer contained the line, Wilder had it pasted in every drawer. Fifty-nine takes were required for this scene and when she finally does say it, she has her back to the camera, leading some to wonder if Wilder finally gave up and had it dubbed.