A bit of irony
Clifford Irving's creation of a "fake" autobiography of Howard Hughes, of which this movie is based, happened in 1971 I presume (that's the publish date for the book).
Irving's most recently published book before that was in 1969, titled "Fake! The Story of Elmyr de Hory, the Greatest Art Forger of Our Time"
How ironic that soon after he published a book, titled "Fake!" about a person who created forged, fake, pieces of art, that Clifford Irving would himself be involved in creating a fake piece of work.