On the boat in the harbor, after Inspector Ahmet tells Dr. Petrie to contact the Home Secretary's office, the sky and weather shift abruptly from blindingly sunny and clear to dark, overcast and windy with choppy seas (as if it were about to rain) for the shots of the scarf.
In scenes that were supposed to have taken place in Turkey in
the 1920s, characters are shown wearing the fez, the wearing of which Turkish leader Mustafa Kemal Ataturk banned (because of its connections with feudalism) in the 1920s.
The first scenes where Fu-Manchu is directing the sinking of the liner were the final scenes of a previous Fu-Manchu movie: The brides of Fu Manchu, where he shots his lieutenant who was trying to stop Fu Manchu surpass the maximum of the machine.
The goof item below may give away important plot points.
Near the end of the movie, Omar is captured in an attempt to free Lisa who evades recapture by hiding near the laboratory where she later watches Omar getting murdered. However, after she escapes the flooding castle, she decides to run back inside to save Omar.