John Lithgow played the part of Harry Zel, a movie agent that Harris contacts after being fired. The part was cut, but there are still references to his character in the film: during the freeway shoot-out, and in the "California Cuisine" luncheon.
While Harris (Steve Martin) and Sara (Victoria Tennant) visit the graveyard, Harris reveals to Sara the tombstone of Shakespeare. This foreshadows their encounter with the gravedigger (Rick Moranis) and resulting conversation which is a spoof of Shakespeare's play Hamlet (Act 5, Scene 1).
There are numerous references to William Shakespeare: the gravedigger scene is from Hamlet, Telemacher quotes Shakespeare twice, and the storyline contains elements from A Midsummer Night's Dream (with the two confused couples exchanging lovers) and The Tempest (with a magic storm stranding the lovers, the gods (in the form of stone lions) blessing the couple, and a character named Ariel).
EASTER EGG: On the DVD, click left on the main menu. When the taillights of the car light up, hit ENTER. A short interview with the director is shown about his opinions of the movie. Also, on the Special Features menu, press left to have the traffic sign light up (says "KISS HER") and you see a similar interview with Steve Martin.
In the very first draft of the script it was revealed that the signs could interact with people because an alien disguised as a repair man tampered with it. The role of the alien was written with Jon Pertwee in mind, he couldn't accept it due to failing health. The script was quickly re-written and the alien was written out.
Sarah Jessica Parker has stated that this film changed her career. Up until this point she had always played mousy girls or the best friend. She said that no one in Hollywood had thought of her as "sexy." Once she was cast in this role several new doors opened for her.