The mermaid costume worn by Doris Day in the opening scene is now on display at the Catalina Casino and can be viewed on the Casino tour.
This was one of Doris Day's last successful films at the box office. Day's manager/husband Martin Melcher had her follow this effort with Desafío en el rancho (1967), Capricho (1967), Anoche cuando se apagó la luz (1968) and El novio de mamá (1968). When three of those four films failed to make money, Melcher negotiated a multi-million-dollar contract with CBS to do El show de Doris Day (1968) (a deal of which Day claimed to be completely unaware until after Melcher's death in April, 1968).
Final film of Alice Pearce. She passed away on March 3, 1966, of ovarian cancer at the age of 48--just three months before this film had its premiere.
This was one of Dom DeLuise's first major roles - his best known credit prior to this film was Just Another Pretty Face (1966).
The song "Soft As Starlight" was co written by Curly Howard, of The Three Stooges fame, along with Joe Lubin.
Doris Day: [song] Day sings "Que Sera Sera" which she also sang in El hombre que sabía demasiado (1956) and No os comáis las margaritas (1960). It was also used as the opening theme music for all five seasons of El show de Doris Day (1968).
Robert Vaughn: briefly appears in his central role of "Napoleon Solo" from El agente de CIPOL (1964) at the party, with a snatch of that show's theme music on the soundtrack. The same music is heard when Homer Cripps goes undercover in drag. Theodore Marcuse played three different guest characters on that show. Dom DeLuise appeared on the spin-off The Danish Blue Affair (1966).
Theodore Marcuse: as Gregor, the cigar-smoking Russian spy. Marcuse was killed in a car accident in 1967, the year after this movie was released.