Both "Less Than Zero" and its reported sequel expected in 2012, titled "Imperial Bedrooms" are named for Elvis Costello song and album respectively. "Less Than Zero" is the first single off of "My Aim is True" (1977), and "Imperial Bedroom" is the name of Elvis' 1982 album.
During American Psycho, the novel (another book written by Bret Easton Ellis), the main character fantasizes briefly about having sex with Jami Gertz (cast as Blair in this adaptation of his first novel) while trying not to pay attention to someone talking to him.
Because the novel didn't have a central plot or a core set of protagonists, but was more a set of interwoven events happening to a larger group of friends, this film differs considerably from the novel. In a surreal twist, the sequel novel, 'Imperial Bedrooms', has the original novel's characters aware of the film version of "Less Than Zero".