Christopher Lee wrote in his memoirs, how his leading lady Tsai Chin assisted him with memorizing the Cantonese dialogue.
In New York City, there was a municipal election being held at the time of this movie's release, and a creative publicist had posters declaring "Fu Manchu for Mayor" printed. Fu Manchu ultimately wound up with a considerable write-in vote on election day.
Christopher Lee (Dr. Fu Manchu), Tsai Chin (Lin Tang) and Howard Marion-Crawford (Dr. Petrie) are the only actors to appear in all five "Fu Manchu" films.
Weather conditions in the Irish locations were damp, bleak, and cold. According to Sir Christopher Lee, everyone came down with the flu because of the freezing conditions, and Walter Rilla almost died.