As well as being an actor, Wallace Shawn (John Lahr) is an acclaimed playwright and screenwriter. Until her 1991 death, his theatrical agent was Margaret Ramsay, who was also Joe Orton's agent, and is portrayed in this movie by Dame Vanessa Redgrave.
Sir Ian McKellen turned down an offer to play Kenneth Halliwell, a role that went to Alfred Molina. McKellen has said that he lived to regret that decision.
Kenneth Halliwell created the title "Prick Up Your Ears" for Joe Orton's (never produced) movie for The Beatles called "Up Against It," but Orton said: "This is much too good a title to waste on a film."
Kenneth Halliwell was actually 25 years old when he first met 18-year-old Joe Orton at RADA. Orton was too young to be conscripted for military service during WWII, but Halliwell was called up in July 1944, when he was 18. He told the draft board that he was a conscientious objector and was instead sent to work in a Lancashire coal mine for the rest of the war.
The title is a naughty pun ("Prick" having both standard and off-color denotations and "Ears" being an anagram for the British spelling of a vulgar anatomical descriptor).