Boris Karloff's character's name in the film is spelled John Ellman in close-ups of teletype and newspaper material in it, but it is misspelled John Elman in its credits.
A train passing through a city would by regulation have to slow down and blow its whistle before each road crossing as well as during its approach to a depot, even if it wasn't stopping at the station. Thus, Blackstone suddenly backing onto a track as a train raced by without warning is unrealistic.
The notion of the state paying a fortune for electrocuting an innocent man is dubious. The prosecutors and courts did everything by the book in good faith and would thus be immune from liability. If anyone (besides the racketeers) was at fault, it was Nancy and Jimmy for not coming forward during the trial or appeals.
When the two crooks shoot at John Ellman, they fire seven rounds from a revolver that shoots only six rounds.
When they lower the glass box over the "dead" John Ellman before he is resurrected, his right eye blinks.