The scene where Graham is advised by (top British royal) The Queen Mother to go on a tour of New Zealand while at medical college actually happened in real life. Animators drawing the sequence showed the Queen Mum wearing a wide hat and pale green dress. Subsequently, home movie footage emerged of her visit taken by Graham on the day, in which the Queen Mum is seen wearing an uncannily similar wide hat and pale green dress. The footage appears in the documentary which accompanies the film, called 'Anatomy of a Liar'.
The audio under the opening credits is from a sketch Chapman regularly used to perform, where he would ask a live audience at the start of the show to give him '30 seconds of abuse', as this would save time later on. For the film, specially recorded abuse was added from John Cleese, Michael Palin, Terry Jones (shouting Medieval curse words), Terry Gilliam, Carol Cleveland and David Sherlock, Chapman's former partner. One of the investors in the film can also be heard shouting "I want my f**king money back!"
In the scene where Graham is reading books in the car with his parents, his father takes the book and puts it in the glove compartment. In the glove compartment are other confiscated books, and behind them a can of Spam. The Spam refers to the (in)famous "Spam" TV sketch by Monty Python's Flying Circus.