Mark Lindsay Chapman was initially cast as John Lennon but lost the part because his name was similar to that of Lennon's assassin Mark David Chapman. Chapman later played Lennon in Chapter 27 (2007).
The docudrama was produced with a great deal of cooperation from Yoko Ono and the Lennon estate.
Mark McGann's elder brother Paul McGann later played the Eighth Doctor in Doctor Who (1996) while Peter Capaldi later played the Twelfth Doctor in Doctor Who (2005).
Mike Myers, who plays the Western Union boy who dresses exactly like John Lennon, has parents who were born in Liverpool.
Sandor Stern was chosen to write and direct after a script by Edward Hume was rejected by Yoko Ono after it depicted too much drug abuse.
Most of the American parts were played by North American actors who lived and worked full time in the United Kingdom. Subsequently many are recognizable from major movies filmed primarily in the UK: Vincent Marzello (Tony Cox) appeared in two James Bond movies and the original 1978 Superman, David Baxt (Elliot Mintz) and Manning Redwood (Houston Magistrate) both played forest rangers in The Shining, and Bruce Boa (Houston lawyer) and Angus McInnes (New York Doctor) are/were Canadians who appeared in The Empire Strikes Back and Stat wars respectively. Finally, Mike Myers (Delivery Boy) was a Canadian living abroad for a brief period before returning to Toronto to join the Second City troupe (which led to his hiring by Saturday Night Live)