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.
Further, the credit "The Artist Formerly Known as Shatner" is a jibe at singer Prince, who for a period of time was known as "The Artist Formerly Known as Prince" due to a conflict with his record company. Shatner's attempt at rapping Shakespeare in the movie includes many Prince song references.
When Bill is pitching the idea for his movie, the 2nd time he takes a drink (right after the waitress brings new ones) you hear ice rattle as he brings the glass up and then back down, but there's no ice in the drink he has.
The movie takes place in 1998 just before Mark's 30th birthday party, putting his birthday in 1968. However, in the flashback scene of Mark trying to get into Star Trek: The Motion Picture Mark says his age is 12 when asked by the women in the ticket stand, despite the fact that Star Trek: The Motion Picture was released in 1979 and the movie itself says 19 years earlier. This would make Mark already 30 by the time the film is taking place in 1998.