The role of Jeff was originally intended for Mothers bassist Jeff Simmons, who quit the group just before filming. As a replacement, Frank Zappa hired Wilfrid Brambell, who walked off the set in a rage a few days later. During a crew meeting, Zappa announced that he would give the part to the next person who walked into the room. Martin Lickert, Sir Ringo Starr's chauffeur, was cast when he walked in with a pack of cigarettes for Starr.
People offered parts in the movie included Vivian Stanshall, Mick Jagger, John Lennon, Pete Townshend, Eric Clapton, Cass Elliot, Grace Slick, George Harrison, Bob Dylan, and Eric Idle.
While Frank Zappa appears extensively in this movie, either conducting the orchestra or playing his guitar, he neither sings nor speaks.
Unlike most movie musicals, the soundtrack was recorded live as the movie was shot, instead of recording the soundtrack beforehand and then lipsynching during filming.