On The Haunting of Hill House, when Theo and Shirley were startled by Nell's ghost in the car, the scene consists of Kate Siegel and Elizabeth Reaser's genuine reactions — Victoria Pedretti made her entrance sooner than they thought.
Creator Mike Flanagan explained, "I just told Victoria before we read the first take to come in substantially earlier than the written cue. The girls had another half page of dialogue to go through as written."
ya i with you but its supernatural i know not how i meet your mother.