The dilapidated area of the hospital in the film was actually a real life abandoned mental hospital, and its state (the paint peeling of the walls and everything falling to pieces) is exactly as the filmmakers had found it.
In one scene, Brigitte's leg gets snapped sideways and she has to snap it back into place. Reportedly, Emily Perkins used her own leg in the shot (as opposed to a prop leg).
Despite prominent billing, Katharine Isabelle (Ginger) appears in approx. 3 minutes of screen time.
The movie that Brigitte watches at Care Facility is Nothing (2003) directed by Vincenzo Natali, who was storyboard artist for the Ginger Snaps (2000).