"Letters" and "Heads I Win" were used in the original London production only and then dropped from subsequent productions. "Chain Letters" was never used.
Julie Andrews was asked to star in the original production. Harold Prince wrote in his book, Contradictions, that she liked the show and wanted to do it, but she was committed fo filming Mary Poppins and asked them to postpone the production for six months so that she could do it. Prince decided to go ahead without her.
Later, she was to star in a film version that MGM was to produce, possibly with Jack Lemmon playing Georg, but in 1969 the film was canceled.
Some time after that, Harold Prince considered directing a film version that would star Joan Hackett and Jerry Orbach. According to his account in Contradictions, the Hungarian government hoped that the film would be made on location there and offered to restore parts of Budapest to what they were like before the war, but Prince could not reimagine the show for the screen and he ended up canceling the project.