- A glass feather is plucked from an ornament. Director Dario Argento's feature film debut was directing Uccello dalle piume di cristallo, L' (1969).
- The first part (with Inferno (1980)) of an incomplete trilogy of films about the "Three Mothers".
- Director Dario Argento, composed the creepy music with the band Goblin and played it at full blast on set to unnerve the actors and elicit a truly scared performance.
- The rich color palette was achieved by shooting in three-strip Technicolor, a process that was already obsolete. But cinematographer Luciano Tovoli found one functioning three-strip camera at Rome's Technicolor headquarters. When the movie wrapped, this camera was dismantled.
- Director Dario Argento's original idea was that the ballet school would accommodate young girls not older 12. However the studio and producer (his father) denied his request because a film this violent involving children would be surely banned. Dario Argento raised the age limit of the girls to 20 but he didn't rewrite the script, hence the naivety of the characters and the occasionally childlike dialogue. He also put all the doorknobs at about the same height as the actress' heads, so that they will have to raise their arms in order to open the doors, just like children.
Please support TCMDB by adding to this information.Click here to contribute