This was the only Hollywood film of the period in which an Asian detective was played by, and top billing was given to, an actor who was actually Asian, in this case Keye Luke.
The last of the six-film Mr. Wong series, and the only one not to star Boris Karloff, replaced by Keye Luke. Monogram owed the distributors one more Wong feature, but had completed Karloff's six-picture contract with the horror film O Gorila Matador (1940).
Possibly the very first instance where Hollywood produced a 'prequel,' because this last entry in the series arguably depicts the first meeting between Mr. Wong and Capt. Street. "Arguably", however, as Wong ages dramatically from this film to the other five films, while Street is seeming the same age and has the same rank in all six, making the tie between this movie and the other five somewhat on shaky ground.
Unusual for its time (and unlike the previous entries in the Mr. Wong series) this film cast an Asian actor as an Asian character, rather than having a European actor play the part in "Yellow Face" (the Asian equivalent of Black Face). British Boris Karloff had been cast as Wong in the five earlier Monogram Pictures. 20th Century-Fox cast Austrian Peter Lorre as their crime-solver Mister Moto, and had two different actors starring as their Chinese detective Charlie Chan, Warner Oland and Sidney Toler, both of Swedish descent. Although Mr. Wong would not continue after this film, Monogram Pictures is to be commended for having the courage to cast Keye Luke in the central role.
The car chase about 30 minutes into the film, ending at a train trestle, was shot along the section of Los Angeles' La Cienega Boulevard that's surrounded by oil wells. It is one of the few parts of L.A. that, even after more than 70 years, still looks much the same.