Hollywood legend claims that, during the filming of Rock Hudson and Doris Day's bathing suit scene (set on a soundstage beach) one of Hudson's testicles kept popping out from his swimtrunks. While screening dailies the next afternoon, the crew laughed so hard, they became teary-eyed, especially when the projectionist figured how to roll the film back-and-forth so it looked like Hudson's testicle was doing a "dance."

All close-up shots of Doris Day are in soft focus.

About a year-and-a-half after completing this film, its twice Oscar-nominated costume designer Irene committed suicide by jumping off the roof of Hollywood's Knickerbocker Hotel. Doris Day, in her 1975 autobiography, suggested the suicide of Irene may have been motivated by the designer's secret, unrequited love for Gary Cooper and Cooper's then recent death from cancer.

Jack Oakie's final movie appearance.

With the death of Donna Douglas on January 1st, 2015, Doris Day was the longest-living member of the cast, until she passed away 13 May, 2019 - 58 years after.

Donna Douglas was cast as Tony Randall's secretary shortly before landing the role for which she is best-remembered; Jed Clampett's daughter Ellie Mae in the long-running CBS sitcom, The Beverly Hillbillies (1962). As the screenplay was co-written by "Hillbillies" creator Paul Henning, it's a pretty safe bet he remembered her when casting the role.

The colors of the smoke in the explosions in Dr. Tyler's chemical laboratory correspond to the ultimate colors of the candy wrappers on the final VIP product.

Whilst Carol is talking to 'Dr. Linus' (actually Jerry Webster) at the aquarium, and talks about trust, and how a woman 'instinctively knows' when a man can be trusted, they're standing in front of a tank mock-up, of what appears to be a large fish, looking to capture prey; what appears to be a small worm. Just when Carol says; 'and, you, doctor, can be trusted,' it turns out the 'little worm' is actually part of a big angler fish, and its huge jaws open and pull in it's prey.

Like its predecessor Pillow Talk (1959), this film was nominated for best original screenplay. Unlike Pillow Talk (1959)., it lost.

The young elevator operator when Doris Day goes to Rock Hudson's apartment after his wild bash ("not a party...THE party!") Is played by Ted Bessell, who was later cast as Marlo Thomas' ever-patient fiancé, Donald, on the late-60s ABC sitcom, That Girl (1966).

Included among the American Film Institute's 2000 list of the 500 movies nominated for the Top 100 Funniest American Movies.

Rebel Davis Edie Adams's husband, the comedian Ernie Kovacs would tragically die in a car crash 2 weeks after the release of this film. Ms Adams did not know how in debt Mr Kovacs was, and was not able to mourn; she had to work - non-stop - first to pay off her husband's IRS bills, but also to have money to live on.

Doris Day passed away on May 13, 2019 leaving none of the credited cast alive

Two conventioneers observe Jerry Webster's continuing antics with multiple women. When later they see him return to the hotel wearing only a full-length mink coat one comments: "He's the last one I would have suspected". This echos much of the world's reaction years later when Rock Hudson's homosexuality became more common knowledge.

The original ending had Carol and Jerry getting drunk on VIP and checking into a hotel. Doris Day insisted the concluding events be rewritten, having Carol and Jerry get married in their drunken state before going to bed.

The proposal the 2 men from the liquor industry make to Jerry - giving him 20% of the $60 million the liquor industry spends on advertising per year ($12 million in 1961) is now worth $97,122,494.43/year.