Although a novel by David Karsner is credited onscreen as the source, none has been located; it may not have been published.
The time period for the end of the film is established in the newspaper item that it had been ten years since Hayden fled to Greece after being indicted. There's no date visible on the paper, but an item next to it showed that it had been 50 years since the death of Scottish physicist James Clerk-Maxwell. Maxwell, who developed the theory that magnetism, electricity and light are different manifestations of the same phenomenon, passed away on November 5, 1879. This would place the date of the newspaper in early November 1929.
Morgan Wallace is listed in studio records in the role of "Pollock", but he doesn't appear in the final print.
Although Robert Barrat is called "Phineas D. Lane" in the movie, he is credited as "Charles Lane" in the credits.