1. Back to the Future
The script for Back to the Future went through several drafts before it was ready to be filmed. Its earliest incarnation was radically different from what ended up onscreen. After sending Marty McFly home, Doc Brown discovers that his time machine runs on Coca-Cola. He decides to abandon his time travel experiment and devotes his life to building flying cars that use Coke for fuel. When Marty arrives in the present, he discovers that the 1980s look a lot like the 1950s vision of the future complete with robot butlers. Rock n Roll doesnt exist because the police had to quell a near riot as a result of Martys anachronistic playing of Johnny B. Goode. So Marty decides its up to him to invent Rock n Roll. If this version of Back to the Future had made it to theaters, chances are itd be a forgotten 80s comedy and wed have had to wait thirty years to find out what the world will be like on October 21, 2015.