The moment in Back to the Future when Michael J. Fox’s Marty McFly masquerades as “Darth Vader, from the planet Vulcan,” is soundtracked by a song that had already appeared in a movie the year before, and starred the actor who was originally cast as Marty. Often heralded not only as one of the best time travel movies of all time but also one of the best movie trilogies ever, Back to the Future remains as popular as ever. That being said, it went through quite a process to end up in its original form.