The reflection of young Norman Bates in the doorknob when he flashes back to his mother's poisoning is Anthony Perkins' son Osgood Perkins.
At time-code 25:10, when Mary and Norman Bates first go into Norman's mother's room, before they turn the lights on, you can see Sir Alfred Hitchcock's silhouette on the wall to the far right.
The original house set was used and the motel was reconstructed.
Producer Hilton A. Green originally suggested Jamie Lee Curtis to play Mary Loomis because of her being the daughter of Janet Leigh and having success with Halloween (1978). Jamie Lee Curtis had a scheduling conflict though, and did not want to return to the horror genre after getting such a huge role in the year's top comedy, Trading Places (1983).
Meg Tilly was never allowed to watch any sort of television as a child, and so had never seen the original Psycho (1960) and was unaware of its significance. She didn't understand why the press was giving all the attention to Anthony Perkins for his comeback role in this sequel, and one day on the set Perkins overheard her say "Why is Tony getting all the attention?" Perkins was upset, didn't talk to her during filming, and recommended that she be replaced, even though half of her scenes had already been shot.
Richard Franklin: As a man standing playing an arcade video game, Battlezone, in the diner that Norman Bates works in, with his back to the camera, but turning his head briefly showing part of his face.