A written prologue after the opening credits reads: "Those portions of this picture dealing with the worship of the goddess Kali are based on historic fact." A 1934 news item in FD notes that Reliance Pictures was planning on producing Gunga Din in 1934. According to a 1938 memo contained in the RKO Production Files at the UCLA Theater Arts Library, Howard Hawks was originally to have directed this film. A HR news item from Oct 1936 announced that Edward Small was producing the Hawks production. Modern sources claim that Hawks lost the job when RKO's 1938 comedy production of Bringing Up Baby went over schedule. Budget details in the Production Files note that William Faulkner, Lester Cohen, John Colton, Vincent Lawrence, Dudley Nichols and Anthony Veiller worked on various treatments and screenplays for the project. News items in HR as well as the Production Files add that the film was shot on location at Mount Whitney and Lone Pine, CA. Over six hundred extras were employed in the Mount Whitney scenes and eight makeup artists were dispatched by Jim Barker, the head of RKO's makeup department, to the Lone Pine set, where they worked for six weeks. News items indicate that some additional location shooting took place near Yuma, Arizona. Telegrams contained in the Production Files note that a character based on and called Rudyard Kipling originally appeared in the film, but when the Kipling family objected in Mar 1939 after viewing the film in England, RKO removed the scenes because the studio feared that the family could win an injunction that would prevent the picture from being shown. Later, Howard Hughes, who owned a controlling interest in the studio from 1948-55, cut twenty-five minutes from the film so that it would fit into a double bill. Thus, many existing prints run 95-98 minutes rather than the original 117 minutes. A news item in HR adds that the film's anticipated release date of Dec 1938 was postponed for retakes.
       Modern sources add that the film cost over two million dollars to produce, and at the time of its production, it was one of RKO's most expensive films. According to modern sources, producer Pandro Berman wanted to make an earlier version of the film starring Ronald Colman and Spencer Tracy. Modern sources also note that Cary Grant was originally offered the role of Ballantine, but preferred the role of Cutter which, at the time, was thought to be a secondary role. Sam Jaffe has said that he patterned his portrayal of Gunga Din after the Indian actor, Sabu. M-G-M's 1951 film Soldiers Three, directed by Tay Garnett and starring Stewart Granger, Robert Newton and Cyril Cusack, was also inspired by the Kipling poem, as well as the film Gunga Din. Robert Coote, who portrayed "Higginbotham" in the 1939 film, appeared in another role in the 1951 picture. The 1962 film Sergeants 3 starring Frank Sinatra, Dean Martin and Sammy Davis, Jr, was also inspired by the Rudyard Kipling poem. The 1962 film, which updated the story to the American frontier, was directed by John Sturges, who worked as one of the film editors for the 1939 film.