William Shatner originally turned down the role as himself. In the original script, Shatner was written as an imaginary mentor who would appear to Mark in times of trouble. But Shatner requested his character to be flawed and more human, which is why he portrays himself as a pompous, lonely drunk in the film. The writers used several anecdotes told by Shatner. The original idea was kept in one scene, in which he appears to Mark as a child.
The credit "The Artist Formerly Known as Shatner in "William Shatner vs. the World Crime League'" is a reference to Le avventure di Buckaroo Banzai nella quarta dimensione (1984), which featured a similar credit at the end of the film, referring to a never-made sequel that appears to have been retooled by John Carpenter into Grosso guaio a Chinatown (1986). The original "World Crime League" reference seems to be a nod to a similar credit at the end of Doc Savage, l'uomo di bronzo (1975).
William Shatner wears the bomber jacket and flight cap he wore as the U.S. Air Force colonel from 12 O'Clock High (1964) after overhearing Mark and Robert's discussion about him.
Phil LaMarr's character is based on Eric Wallace. According to LaMarr, the real Eric is so loud and excitable that LaMarr had to resist doing an impression of Eric when playing him.
In a deleted scene, Leila, played by Lori Lively, says she appeared in Deep Space 9. Lori Lively appeared as a Cardassian named Siana in the Star Trek: Deep Space Nine episode "Shadows and Symbols" in 1998.