Esmeralda (the witch) wears a costume from Glen A. Larson's TV series Buck Rogers in the 25th Century (1979): it was originally worn in Flight of the War Witch (1980) by guest star Julie Newmar, whose character Zarina was referred to as "the war witch". Several other costumes from that series can also be seen when Michael is searching through the racks in a costume shop.
Kurt Paul plays Norman Baines, which is a reference to Norman Bates, played by Anthony Perkins in Psycho (1960). Paul was Perkins' stunt double in Psycho II (1983) and Psycho III (1986), He also played the role of Norman Bates in Bates Motel (1987) and later appeared in Psycho IV: The Beginning (1990).
Michael actually breaks into the Central Costume store. When a security guard disturbs him, he calls on K.I.T.T. for a diversion: K.I.T.T. animates a suit of armor to scare him silly. The sequence is cut from the episode.
Norman Baines is wearing a mask at the foundations Halloween party it appears to be a mask with the silver shamrock on it from Halloween 3 season of the witch.