The title was changed to "Cracking Up" so late that when the characters go to see this movie, the marquee of the theater still has the original title "Smorgasbord".
Jerry Lewis plays ten different roles in this movie. These included Warren Nefron, Dr. Perks, a gangster, a six year old, Speed Armeter and an elderly guru. Co-writer Bill Richmond played five different parts.
Writer Bill Richmond once said of working with Jerry Lewis: "All I do is write down everything Jerry says and then sell it back to him".
The film marked the reunion of actor-director-writer Jerry Lewis and writer Bill Richmond who had last worked together during the 1960s. The two had previously successfully collaborated on such movies as The Patsy (1964), The Bellboy (1960) and The Nutty Professor (1963). The movie represented their seventh and final collaboration.