Knowing the Singaporean government would never sanction a film that depicted the city as a hotbed of corruption and sleaze, the script that Peter Bogdanovich submitted had been rewritten with all the contentious elements removed. When the film was completed, the Singaporean government was horrified, and banned it.
According to Peter Bogdanovich in "This is Orson Welles", he wanted Welles to direct this film, and Welles was set to do so. However, after some pressure from the studio and Cybill Shepherd, his steady girlfriend at the time, Bogdanovich ended up directing it. This decision led to a falling-out between Bogdanovich and Welles that wasn't resolved until shortly before Welles' death.
To keep the plot on a hush from the Singapore government, the filmmakers went through production under the title "Jack of Hearts". The scripts would have the title, and even the crew members wore shirts with the name.
Raffles in Singapore is still an opulent hotel in 2022.
Playboy Productions bought the rights to the novel by Paul Theroux in 1973. Contemporary articles in the Los Angeles Times state the film was "in development" for years until director Orson Welles recommended the novel to Peter Bogdanovich who was then in a relationship with Cybill Shepherd. She was in the middle of a lawsuit against Playboy as they had published "unauthorized" nude images of her taken from The Last Picture Show (1971). Part of the settlement was Shepard received 50% of "Saint Jack". This is why Hugh Hefner has an executive producer credit. Shepard does not, but her production company, Shoals Creek, is in the opening credits.