E.G. Marshall and Jack Klugman both appeared in the classic 12 Angry Men (1957). They were Juror #4 and Juror #5, respectively.
Alfred Hitchcock's greeting is, "Oh, hello, fellow speculators" instead of his usual "Good evening".
Grimes receives a personal letter at his office from the "prophet". A closeup of the envelope reveals that Grimes' office is on Revue St. in New York City. Revue is the MCA/Universal division that released and distributed "Alfred Hitchcock Presents".