Jessica Rains - seen briefly as the employment agency clerk - is the daughter of Claude Rains who had three times co-starred with Bette Davis in Now, Voyager (1942), Mr. Skeffington (1944), and Deception (1946).
The film was shot on location at the Sunset Strip mansion of Howard Hughes' former partner, Noah Dietrich.
Filmed at the Noah Dietrich estate at 1486 N Sweetzer Ave, Los Angeles, CA in the Hollywood Hills just above Sunset Blvd.
The Bette Davis scene on the cover of the Kino Lorber Blu Ray, with her back slightly turned while she turns and looks into the camera, is taken from exactly 12:46 when she's getting a hidden bottle behind books on the bookshelf, although on the cover only she is shown with knife superimposed to her left.
Bette Davis has a similar role in another horror movie, Burnt Offerings, again as a mother holed-up in the upstairs room of a mansion.