Lorne Chumley is a parody of the silent film star Lon Chaney Sr., but also includes some aspects of his son Lon Chaney Jr.
Don Adams' speech patterns resemble Agent Maxwell Smart, his character from Get Smart (1965). He later recycled these same traits into his animated title character in Inspector Gadget (1983).
Velma tells Scooby-Doo "Not everybody can be a movie star." He did actually become a movie star later on in Scooby Goes Hollywood (1979).
The plot is somewhat similar to Robert Arthur's 1964 juvenile detective novel The Secret of Terror Castle, the first book in the "Three Investigators" series.
The Wolfman and Frankenstein portraits bear a resemblance of the monsters from A Gaggle of Galloping Ghosts (1969). A portrait of Swampy Pete from The Ghostly Creep from the Deep (1972) is also seen.