Back To The Future's Original Plan For Time Travel Was Too Expensive
Other than Doc Brown's gloriously wild halo of hair, the first thing everyone thinks of when they hear the words "Back To The Future" is that sweet-ass DeLorean, with its super cool vertical hatch doors and magical time-travelling abilities. Sure, the hoverboard is cool enough, but it can't hold a candle to that iconic car.
The Original Plan
Which is why it's almost blasphemy to learn that the DeLorean was supposed to be a pickup truck, and the time machine itself was a laser device inside an old-timey refrigerator in the back of said pickup. In the original draft, getting back to the future wasn't a matter of collecting energy from a clock tower during a perfectly-timed lightning strike; Marty was going to get back to 1985 by driving into a nuclear bomb explosion.
Universal Studios Originally, the flux capacitor was a wishbone left in there from Thanksgiving.
Which would have been a reasonable plot point, considering the American government was testing nuclear bombs left and right in the Nevada desert during the 1950s. So initially, when it was time to get Marty back to 1985, Doc and Marty would go to the desert, attach the laser-time-travel thing to the refrigerator, strap the refrigerator to the truck, instruct Marty to get in the refrigerator, then rig the truck so that it drives straight into a nuclear bomb explosion, where the whole contraption would get propelled through time. If this sounds familiar, it should. The concept was rejiggered for Indiana Jones And The Kingom Of The Crystal Skull.
Lucasfilm Note: We didn't say "rejiggered well."
There were two problems. One: Filming on location in Nevada wasn't in the budget. Two: Creating the effect of a nuclear explosion would cost a million dollars, according to Industrial Light & Magic -- which was money the team didn't have. Oh, and Zemeckis was also noticing that there was a rash of incidents wherein kids would crawl into old-fashioned refrigerators and get stuck inside after they latched shut. Attaching his name to action movie that might inspire more child suffocation deaths AND more nuclear explosions didn't sit well in his stomach. So they compromised by switching the time machine from a thermonuclear refrigerator to a terrible sports car designed by a cocaine trafficker.