The episode opens with a hallucinating Ross singing the psychedelic lyrics to a song. Cannon later recites the lyrics to a disc jockey friend who identifies them as the T. Rex song "Baby Boomerang." While not performed, actors John Vernon and William Conrad each warble snatches of the lyrics. The song appears on T. Rex's celebrated 1972 LP "The Slider."
The title refers to the "Hard Rock Cafe" chain founded in 1971 by Americans Peter Morton & Isaac Tigrett in London and known for their restaurant walls that were covered with music memorabilia.