Fans of Back to The Future know that the basic plotline of Back to the Future Part II was about Marty McFly and Doc Brown finding themselves in an alternate present ruled by Biff Tannen, and going to the year 1955 (where the events of the original movie took place) to Set Right What Once Went Wrong. But did they know that they were originally not going to 1955, but 1967? You can find the full script here.