The "glass heart" machine used to revive Karloff's dead character was said to be "nearly a prefect replica" of an actual perfusion pump--a device designed to keep organs alive outside an organism's body--which had been built by Charles Lindbergh, when the legendary pilot and engineer was working with a Nobel-winning scientist at New York's Rockefeller Institute research labs in the mid-1930s.
The music being played while Karloff is walking to his execution is Kamennoi-Ostrow by Anton Rubinstein.
The accident scene was shot in Griffith Park.
Filming began on November 23 (Boris Karloff's 48th birthday) and lasted 18 days, finishing December 23 1935.
The $500,000 John Ellman wins in his lawsuit against the state would be the equivalent of over $8,550,000 in 2015.
Boris Karloff's character was originally conceived as 'Dopey' Ellman and was a drug addict and alcoholic.
Nicholas Kobliansky (Russian Doctor), Edward Peil Sr. (Train Engineer) and Adrian Rosley (Florist) are listed in studio records as actors (with their character names) in this film, but they do not appear.
It has been stated in later years by film historians, that director Michael Curtiz made the film as quickly as possible so he could proceed to more important films.