Thank you! It's great that you took a look at this film! Yes, it had its beginnings as "Charlie Chan at the Ringside." The story of how Warner Oland was suffering what was surely a nervous breakdown as production began, and his walking off the set, thus curtailing the filming, is a sad one. He was going through a lot in his life at the time, including his separation from his wife, Edith, and alcohol was certainly a factor as well, possibly exacerbated by other stresses in his life.
To salvage what they could of the movie, 20th Century-Fox brought in Peter Lorre and re-tooled the film as a Mr. Moto picture. Keye Luke, who was retained as Chan's Number One Son, Lee, who is participating as a part of Moto's criminology class. I think that this would have been the same, basically, if it had been a Charlie Chan movie.
You probably noticed how "Mr. Moto's Gamble" has the unmistakable "feel" of a Chan film from beginning to end. We even hear Mr. Moto uttering "Chanisms" that were undoubtedly meant for Warner Oland's dialogue. I am pretty sure that the original script was basically unchanged, and I have no trouble picturing Warner Oland whenever we see Peter Lorre on-screen! In my opinion, "Mr. Moto's Gamble" could be considered an "almost" Charlie Chan movie!
I fully agree. I also noticed that Lon Chaney Jr. had a bit part as a thug. This would have been a couple years before his fame as the Wolfman. All together a very interesting film.