Great Scott! Did you know that Back to the Future was never supposed to have a sequel? Imagine that reality for a second — a world without Marty McFly's hoverboard and shoes and flying DeLorean? The mind reels!
Director Robert Zemeckis explained it all in Empire magazine's oral history of Back to the Future:
We'd never designed the first Back To The Future to have a sequel. The flying car at the end was a joke, a great payoff. We thought this would be really hard to unravel and do again. But when you make a movie that's as successful as Back To The Future, it becomes this piece of corporate real estate. It becomes bigger than you as a filmmaker. You're basically given a decision: we're making a sequel, do you want to be involved in it or not? So we felt we had to protect our work.
So there you have it. The flying car at the end of the first Back to the Future was supposedly just a throw-away joke. But consider me at least somewhat sceptical. Zemeckis has lied to us before. Damn you Zemeckis! Where's my hoverboard?!!?! [Paleofuture]