Despite the lightweight nature of the film, it was budgeted at $300,000.00, (about twice the amount of a typical Universal B-feature of the time) making it one of the studio's most expensive productions for 1940.
Margaret Sullavan, who owed Universal one picture on an old contract, was originally assigned the starring role. With more attractive roles being floated her way, she balked at appearing in the film, feeling it was beneath her. After she failed to appear for the rehearsals, the studio slapped her with a restraining order preventing her from working anywhere else. Eventually, she agreed to fulfill her contract by appearing in Back Street (1941) and Virginia Bruce stepped into the role.
Due to his long-term alcoholism, John Barrymore had difficulty remembering his lines which had to be written on cue cards and attached to walls, the floor, or any other object off camera so he could read them. When one watches his performance as he talks to another character, his eye line noticeably moves in various directions as he reads.
This is the first film in The Invisible Man series of classic Universal horror films in which the titular invisible person (in this case, a woman) is not already invisible at the start of the film. As such, it is the first in the series in which the audience sees the process of the person being made invisible.
This is the first film in The Invisible Man series of classic Universal horror films in which the invisible person (in this case The Invisible Woman) is shown in visible form for more than a few brief seconds. She is visible for a significant portion of time throughout the film.