Several key cast members in the film are uncredited and their identities remain unknown, most notably the cat-farming neighbor, "Goof", as well as the detective, the skinny morgue attendant, and Maria Altura, the woman who Dr. Meirschultz brings back to life. The identity of the actress who doubles for Altura for scenes that require nudity has also not been identified.
The film contains intertitles, a few comment on the action in the film as they were used in silent films, but the majority, five of them, comment on the then prevailing descriptions of various mental illnesses: Dementia Praecox (now called Schizophrenia), Paresis (here used to refer to the latter stages of syphilis), Paranoia (actually listed as a noun "Paranoiac"), Manic-depressive Psychoses (now usually referred to as Bipolar Disorder), and Manias.
Author and historian Bret Wood has posited that the backyard cat farm seen in the film was a real, illegal operation in somebody's backyard in a Los Angeles suburb. He also suggests that some of the sets for the film, namely the morgue, were found or rented rather than being built by the filmmakers.