Trivia

Begun as a Charlie Chan film ("Charlie Chan at the Ringside"), but after difficulties between 20th Century-Fox and Chan star Warner Oland, the script was hastily rewritten to accommodate Fox's other Asian sleuth, Mr. Moto. The presence of Chan's son Lee is evidence of the grafting of one movie onto another series. Producer Sol M. Wurtzel specifically ordered the writers to include Keye Luke's character in the revised screenplay. Though it has been reported that Oland's death was the reason for this change from Chan, this was not the case. This film was released theatrically on 3/25/38; Oland died on 8/6/38.

While talking to Lee Chan, Harold Huber as Lt. Riggs refers to working with Lee's father Charlie before. In Charlie Chan on Broadway (1937) Huber played another New York policeman.

The only non-Chan film to feature Keye Luke's Lee Chan character, and the last at Fox. Luke would play Lee twice more, in Monogram's final two Chans, The Feathered Serpent (1948) and The Sky Dragon (1949).

This was the third Mr. Moto film to be released and, based upon a salvaged Charlie Chan script, it was the first in the series in which Mr. Moto does not kill an adversary. He would make up for it in the next film in the series by killing at least a half-dozen.

Filming began on this film as "Charlie Chan at the Ringside" with Warner Oland. He was, however, was in the midst of a messy and emotionally disruptive divorce, making him much more temperamental and unpredictable than usual. During the first few days of filming, Oland would walk off set and not return for the day or he would simply not show up to work, thus costing the studio thousands of dollars and wasting the time of all of the cast and crew. After several days, Oland refused to work on the set (which was located on the older and draftier Studio Six) where he claimed he would catch pneumonia. Oland, an early member of the Screen Actors' Guild, put the guild in a tough situation of either challenging a studio over what was really the capricious demands of a temperamental actor or appearing to be indifferent to the health concerns of a guild member. The studio remedied the situation by simply painting a seven over the six on the door of Studio Six. Oland, none the wiser, fell for the trick and returned to work for a few days. After only three days of filming, however, Oland left the set to ostensibly get a drink of water and never returned. That day would be the last that any of his Charlie Chan family would see him. Feeling the sting of his divorce, Oland returned to his native Sweden to visit his mother. Tragically, and ironically, he caught pneumonia at her house (the very thing he feared of getting in Studio Six) and passed away. The film he had been working on, "Charlie Chan at the Ringside", became this film: "Mr. Moto's Gamble". Oland was replaced and the film was completed well before his passing.