The original script was a Charlie Chan murder mystery titled "Charlie Chan at Trinidad" to star Warner Oland. However, due to Oland's untimely death, the entire script was re-written in only a few weeks to star Peter Lorre as his Mr. Moto character.
Last of Fox's eight Mr. Moto features starring Peter Lorre, but the seventh to be released (though completed two months earlier, Mr. Moto Takes a Vacation (1939) was distributed last). This was also the second Mr. Moto entry (after Mr. Moto sur le ring (1938)) that was originally written as a Charlie Chan script (and both entries were the only ones not directed by Norman Foster). The character returned only once, in a low-budget, black-and-white second feature produced in England, The Return of Mr. Moto (1965), starring Henry Silva.
According to Jon Tuska's "The Detective in Hollywood" Leon Ames claimed that Peter Lorre's teeth were in really bad shape, resulting in the star having very bad breath.
At 48 minutes, this is the same dock set as used in "Mr. Moto's Last Warning".
In this eighth entry (the seventh to be released) in the Mr. Moto series, Willie Best was used again as he was in "Mr. Moto Takes a Vacation" (1939) as a black comic relief character.