According to the DVD sleeve notes, prior to production,
James Cagney trained intensively in the martial-art of judo in preparation for his role in this movie. Cagney trained under Ken Kuniyuki who was a 5th Degree Judo Master. Cagney insisted he perform his own stunts in the movie. Moreover, another instructor for Cagney was former policeman
John Halloran who plays the role of Captain Oshima in the film and can be seen in the movie's closing fight sequence.
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