According to the DVD sleeve notes, prior to production James Cagney trained intensively in the martial-art of judo in preparation for his role. He trained under Ken Kuniyuki, who was a 5th Degree Judo Master. Cagney insisted that he perform his own stunts. He said in his memoirs, "I grew so fond of judo I used it to keep in shape until a back injury I picked up doing something else put me on the sidelines." Moreover, another instructor for Cagney was former LAPD policeman John Halloran, who plays the role of Capt. Oshima and can be seen in the closing fight sequence. Apparently Halloran quit the LAPD after FBI agents investigated him because he was an expert in judo.
The DVD sleeve notes claim that this was one of the first American martial-arts movies. Though not a martial-arts movie by modern standards and definitions, judo is seen in the movie and with James Cagney performing it. Cagney insisted on doing his own stunts in the film.
The movie is based on the history behind Japan's alleged Tanaka Plan, aka the Tanaka Memorial document (it was made public after his death in 1929). This allegedly was Prime Minister Baron Gi-ichi Tanaka's militarist strategic plan for world domination prepared for Emperor Hirohito. It was first printed in China by the Chinese communists and in the US by a communist periodical, leading some to think that it was a forgery. No Japanese version has ever been found.
The Japanese Tanaka Plan was examined in the documentary The Battle of China (1944)], episode 6 of the "Why We Fight" series by Frank Capra. According to the book "Brassey's Guide to War Films" by Alun Evans, this movie is "fiction highlighting fact, but a strange release date. One would have thought that the unearthing of the Tanaka Plan . . . might have received dramatic attention by Hollywood before Pearl Harbor, rather than at the end of the war. The Tanaka Plan, the blueprint for Japanese world domination--which actually specified the taking out of Pearl Harbor--was uncovered in 1927, but this dramatisation has [James] Cagney as U.S. newspaper man in '20s Japan printing the story."
James Cagney has long being associated with the phrase "You dirty rat!". Though he actually said in the movie Taxi (1932) "Come out and take it, you dirty, yellow-bellied rat" and not "You dirty rat!", Cagney is heard saying "dirty rats" in this movie.
Robert Armstrong, who played Tojo, wore a set of false teeth to make his jawline as much like Tojo's as possible. However, with the teeth in place, when he spoke his lines he could not be understood. So back to the studio he went, to stand in a soundproof booth and loop his lines, making what his character said understandable.
When Iris Hillaird (Sylvia Sidney) tells Nick Condon (James Cagney) that they cannot be together because she is half-Japanese and half-Caucasian, Condon replies that he too is of mixed race. "I'm half-Irish and half-Norwegian." In real life, James Cagney was the son of an Irish-born father and a Norwegian-born mother.
The film has largely fallen out of favor in recent years because of its overt anti-Japanese propaganda angle, and because of the casting of several actors of European heritage as Asians. This practice has begun to be referred to as "yellowface" casting.