Working title Paradox on clapboard.png|Paradox working title on Back to the Future Part II clapboard. Paradox Production Back to the Future Part II.png|No Admittance Paradox Production Crew Only. Paradox was the name of a proposed sequel to Back to the Future that combined the plots of Back to the Future Part II and Part III into one film. However, the producers of Back to the Future decided to not use this draft of the screenplay because it would be too expensive, and rewrote the screenplay as two separate films. Nevertheless, Back to the Future Part II was still shot under the working title Paradox. This was done to try to lessen the amount of publicity.