Jon Lovitz auditioned for the movie when Howard Zieff was the director, and wasn't cast. When Penny Marshall took over from Zieff, she offered Lovitz a role. She was friends with Lorne Michaels, and had seen Lovitz's work on Saturday Night Live.
According to Penny Marshall's memoir 'My Mother Was Nuts,' the script had numerous versions. Nancy Meyers and Charles Shyer wrote one for Shelly Long as the star. A version by David Mamet was filled with profanity.
Adding to the classic rock theme running throughout the movie, Terry's boss' name is James Page (guitarist from Led Zeppelin).