The Hollyrock movie stars cast in "The Monster from the Tar Pits" are Gary Granite, Rock Pile, and Wednesday Tuesday. Gary Granite is clearly a spoof of Hollywood leading man Cary Grant (even imitating his speech), Rock Pile is a spoof of leading man Rock Hudson, and Wednesday Tuesday is a spoof of Tuesday Weld.
ABC originally broadcast this episode in black and white.
One of the people auditioning for a part in the movie plays The Flintstones theme song on a harmonica.