John Huston was not fond of the finished film, saying it had been impossible to make it under the Hays Code.
Robert Mitchum had just returned from spending four months in Tobago filming Fire Down Below with 'Jack Lemmon' and Rita Hayworth when he learned that his agent had committed him to this movie, filming in Tobago.
After spending so much time in Trinidad/Tobago, Robert Mitchum became enamored with Calypso music, so much so that he recorded an album of the stuff. It was called Calypso - Is Like So, and was released on Capitol Records. It features him doing spot on imitations of the style and is still available on CD.
Mitchum was very enthusiastic about playing the role of the marooned corporal until he learned that director John Huston had first tried to interest Marlon Brando in the role.
Originally when filming began on Heaven Knows, Mr. Allison, her co-star Robert Mitchum worried that Deborah Kerr would be like the prim characters she frequently played. However, after she swore at director John Huston during one take, Mitchum, who was in the water, almost drowned laughing. The two stars went on to have an enduring friendship which lasted until Mitchum's death in 1997.
Supposedly Robert Mitchum's favorite film role he played.
The director and the explosives expert were reportedly left hanging onto an elevated platform on location - uninjured - after a short-circuit in explosives-effect wiring unexpectedly set off all of some 30 planted detonation devices at one time.
The knife used by Cpl. Allison is a Ka-Bar. It is standard issue for the US Marines since 1942.
The script called for several Japanese-speaking officers and a company of Japanese troops to be on the island. There were no Japanese men on the islands of Trinidad and Tobago, where the film was shot. A half-dozen who spoke the language were finally found in a Japanese emigrant community in Brazil and flown to the location to play the officers. For the non-speaking roles of Japanese troops, the company hired 50 Chinese who worked in the island's restaurants and laundries. This caused friction with the local islanders, who found it difficult if not impossible to get their clothes cleaned or to get a meal in a restaurant because most of the employees were working on the film.