Eric Idle wrote and sang the song "Harry" as thanks to Harry Nilsson for recording Idle's "Bright Side of Life" on Nilsson's Flash Harry album.
Nilsson wrote and performed the song "Men At Sea" for the film Yellowbeard which starred several members of Monty Python. The song was not used in the film but does appear at the end of Group Madness, a documentary about the filming of Yellowbeard.
During a Monty Python concert, Harry joined the group on stage to sing the "Lumber Jack Song." An enthusiastic fan in the audience reached up to shake Harry's hand and accidently pulled him off the stage. Harry broke bones in both hands.
Graham Chapman was godfather to one of Harry Nilsson's children.
Harry Nilsson wrote the foreword for Kim "Howard" Johnson's Life Before and After Monty Python: The Solo Flights of the Flying Circus.