Helen Hayes had previously played Abby in a television broadcast on January 5 1955.
In his vocal interpretation of the monstrous Jonathan Brewster, Fred Gwynne offers an uncanny tip of the hat to the role's legendary originator and inspiration, Boris Karloff (in further homage, with tongue firmly in cheek, Gwynne's maniacal laugh is pure Herman Munster). While most actors have portrayed Jonathan in purely menacing terms, Gwynne's portrayal is comically idiosyncratic, lending a dash of authenticity to his being a blood relative of the eccentric Brewster clan.
The play's most famous line, "He said I looked like Boris Karloff!" - written to be spoken by Karloff himself in the original production - was changed here to "He said I looked like Frankenstein's monster."
The role of Dr. Einstein (Jack Gilford), Jonathan's plastic-surgeon accomplice, is rechristened Dr. Herman Salk, a macabre homage to Dr. Jonas Salk, who discovered the polio vaccine.
As the character of Elaine (Sue Lyon) is no longer the Brewsters' next door neighbor, impatiently awaiting Mortimer's return, it is never sufficiently explained as to why she disappears from the action for nearly all of the third act of this production.