Despite having the same surname as three other invisible men, Robert Griffin (Jon Hall) bears no relation to them.
This is generally considered to be Universal's last entry in the 'Invisible Man' series. Seven years later the studio spoofed the series with Bud Abbott and Lou Costello Meet the Invisible Man (1951).
Although Dr. Drury calls his dog Brutus, the canine actor is given an "Himself" credit as Grey Shadow.
Jon Hall had played an Invisible Man character for Universal in Invisible Agent (1942), two years before this film.
Character actor Edgar Barrier, unhappy with the way his career was shaping up at Universal, dropped out four days before production began. He was quickly replaced by Lester Matthews.