The last film in which Jack Hawkins' (the British Ambassador) voice is heard. In subsequent films he would be dubbed by other actors due to his problems with throat cancer.
The film was shot in the first part of 1967, but was not released until right at the end of 1968; it was a box-office and critical disaster and has been rarely seen since.
Original director Elliot Silverstein, of Cat Ballou (1965) fame, quit after constant disagreements with star and co-producer Peter O'Toole. Silverstein reportedly claimed that he "wouldn't be a star's lackey", a remark which offended O'Toole greatly. He was replaced by Gordon Flemyng, who had just finished directing O'Toole in a television play.
[prologue] "Mr Shaw stated that Historical Portraiture was not the motive of this story and the Producers would like to add that any similarity to any Historical Event will be nothing short of a miracle."