Peter Sellers was legendarily difficult during the making of this film, even falling out with Kenneth Griffith, one of his best friends. He was most hostile towards director Robert Parrish, and made determined efforts not merely to undermine him but to replace him as director. Until a short time before the film's release, it seemed that he would get a co-director credit. But eventually, Parrish got sole credit - some have unkindly suggested that Sellers waived his claim because he knew the film would be a critical and financial disaster (which it was). Sellers and Ekland were also having marital difficulties during the making of this picture and would divorce the year after its release. Sellers' mother also died during production.
Perhaps as an in-joke, Peter Sellers is whistling the theme to A Man and a Woman (1966) to himself in one scene. The tune was written by Francis Lai, who composed this movie's score.
An article in the 26 July 1967 edition of Variety noted that director Robert Parrish wanted to make a sequel titled "The Further Adventures of Olimpia", to star Britt Ekland.
The car Olimpia drives at the beginning of the film is a 1963 Triumph Spitfire 4. The blue car she stops to admire is a 1965 Maserati Mistral Spyder. Only 125 of the Spyder convertibles were made from 1963 to 1970, and one in excellent condition in 2020 could be worth well into six figures.