Jennifer Connelly had part of her finger bitten off by the chimpanzee in the final scene at the end of the film. She was rushed to the hospital and the finger was re-attached.
Jennifer Connelly said in an interview that she was bitten by the chimp in this film. Apperently during one scene the chimp kept turning around and Dario Argento, not wanting to film her behind, asked Connelly to place her hand on the animal to stop her from turning. But when she attempted to do so, the chimp became enraged and bit her; and then became very hostile toward Connelly for the rest of the film.
(at around 15 mins) The story Jennifer tells about her mother abandoning her was an actual story from Dario Argento's own childhood.
The imagery, aesthetics and several plot points from this film (as well as a handful of elements from other Dario Argento films) served as inspiration for the survival horror video game Clock Tower (1995). The game follows a teenage girl named Jennifer Simpson (whose appearance is modeled on Jennifer Connelly's from this film), who is trapped in a sprawling mansion estate with a psychotic, deformed boy wielding a giant pair of scissors.
Shot in English and dubbed into Italian.