Publicity for this film stated that this was the comeback movie for actress Carrie Snodgress who had not appeared in a theatrical film for eight years (since 1970 when she appeared in both Rabbit, Run (1970) and Diary of a Mad Housewife (1970)), her last credit at the time having being seven years previous in the 1971 tele-movie The Impatient Heart (1971).
For her role as a psychic with telepathic powers, Amy Irving attended a biofeedback clinic to learn about different levels of consciousness. After personally experiencing psychic changes, she had a better sense of how her character could transmit and receive messages.
When Peter Sandza's car is chased by the police on the Pier, you can clearly see the head of a crew member on the left of the screen. The camera is moving left to right, and the technician was probably running for the traveling beside the camera.
Peter shoots out of the open car window to help Gillian, this causes the crash that Hester ends up involved in. After Gillian's shock it Pan's to Peter, his face shoved against the now closed window, it flattens part of his face then lifts and wrinkles the rest. When he gets out to run to Gillian to shot the guy grabbing her, the car door swings out and you see the window is once again open...
Woman gets run down by a current model Ford. She crashes through the windshield, which is made of plain glass. Since 1966, all cars made in the United States have safety glass in the windshield.
Mother Nuckells: I'd say I'm pretty sound, considering the ravages o' time. For instance, I don't have the use of any more than one of my limbs or vital organs. Good thing the Lord God Jehovah built in so many spare parts.