Boris Karloff only really played Dr. Jekyll in this film. Once the makeup transformation scenes were over, stuntman Eddie Parker did every scene as Mr. Hyde. This was even tipped off to audiences through publicity stills for the film, which showed both Karloff and Parker in makeup standing next to each other.
In Britain it was given an X certificate though it later played on children's television.
Unlike other versions of Dr. Jekyll & Mr. Hyde, this time Jekyll is pretty evil in his own right. He seems to have no qualms about deliberately becoming Mr. Hyde so he can commit a murder.