When this serial was made, there was a moratorium on horror films, brought on by Joseph Breen of the Hays Office. Consequently, Boris Karloff did thrillers at Warner Bros. (but not really any horror films), and Lugosi did poverty row movies and serials. Of the latter, this one I think is his best, but his having the name "Boroff" plus his using a ship called the "Cairfax" (as in Cairfax Abbey, where Dracula stays in London) are obvious in-jokes, though I doubt they were of Lugosi's doing.