Fidel Castro's government gave permission for this film, which presents the fallen regime of Fulgencio Batista, in an unflattering light and also condemns American and British meddling, to shoot on location in Havana, only months after the revolution. It was completed during the brief period in 1959 before Cuba had aligned itself with the Soviet Union.
Alec Guinness originally wanted to play his character as an untidy, defeated soul instead of a generally hapless non-entity.
Jean Seberg was considered for the role of Milly.
Ernie Kovacs reportedly smoked 25 Cuban cigars every day.
Alfred Hitchcock was interested in making a film based on Graham Greenes novel. The writer wasn't keen on Hitchcock, however, after his days as a film critic, so he chose to work instead with Carol Reed.
Brazilian director Alberto Cavalcanti had originally been in talks with Graham Greene about making a film together just after World War II. They had devised an outline story about a vacuum cleaner salesman operating as a spy in the Estonian capital of Tallinn in 1938. This project stalled when they were refused government permission to lampoon the Secret Service. Undeterred, Greene carried on under his own steam, drawing on his experience observing Abwehr (German intelligence service) agents in Portugal during World War II, who had been paid per report and not according to results.
Cinematographer Oswald Morris deliberately lowered the light levels in the Havana locations to make them more atmospheric.
Englishman Jim Wormold is raising his daughter, Milly, as a Catholic on the wishes of his estranged wife, although he is not Catholic. Alec Guinness and the book's author, Graham Greene, were Englishmen who converted to Catholicism. Guinness and his wife converted in 1956.
Filmed on location in Havana three months after Fidel Castro's January 1959 revolution, the script had to be submitted to Cuba's Ministry of the Interior, which insisted that 39 changes be made to make it appear that life during the Batista regime was more unfavorable.
Several times during the film, one can see the neon business sign next door to Mr. Wormold's building which boldly reads "BOND". It is an obvious nod to Ian Fleming's popular spy novels of the time.
Shooting at Shepperton Studios lasted 11 weeks.
The car Millie shows interest in at the end of the movie is a 1957 Jaguar Mk.VIII
The comic strip Rock Kent in the newspaper is credited to a Syd Cain. Syd Cain was the movie's assistant art director.
The Cuban scenes were filmed over a period of five weeks, and were frequently interrupted by local Cuban residents getting very excited by all the filming.