In an odd twist of fate that could not be appreciated for at least a decade, Karl Malden plays a hotel thief who breaks into guest rooms and steals wallets; following one lowly heist that nets him him only a few dollars in actual cash, he bemoans that his livelihood is being snuffed out by rampant popularity of credit cards - which ironically later became his real-life late-career claim to fame as spokesman for American Express credit cards: "Don't leave home without it!"
The character of "Curtis O'Keefe" was based on Conrad Hilton, who shared many characteristics with the O'Keefe character including owning a large chain of hotels, many of them acquired properties, being accompanied by beautiful women and praying in meetings.
The "Hotel St. Gregory" was based on the Hotel Roosevelt in New Orleans, which at the time the novel was written was in the process of being sold by its elderly owner Seymour Weiss, who has started his career managing the hotel's barber shop, to the owners of the Hotel Fairmount in San Francisco. Coincidentally, when the novel was adapted as a TV series, the Fairmount San Francisco was used a film stand-in for the "St. Gregory" (with the show's location changed to San Francisco.
The jewelry worn by Merle Oberon as the Dutchess Caroline were actually her own. At the time they were valued at $500,000. The jewelry also included a piece that, at one time, had been worn by Marie Antoinette.