If you've ever had a fantasy about time travel, chances are it's been sparked by Back To The Future. Even if the scenario in your head is in no way related to hitting on your mother's younger self or fighting cowboys, then the mechanics of you how you get back to that point (you sicko) have been the same as they are in Robert Zemeckis's classic trilogy of blockbuster sci-fi films. The rules of time travel as they exist in Back To The Future are by no means watertight or foolproof, but they were never meant to be. They're just fun films. That's why they can be applied to day dreams so easily. It's also why said day dreams and, consequently, the films can be torn down so easily. Give even the slightest amount of serious thought to all of the timeline-altering, paradox-creating actions that occur throughout all three films, and suddenly it becomes a wonder the entire universe didn't collapse in on itself. Sure, Doc Brown pays lip service to the idea that they could create rips in the very fabric of reality, but he's still all for messing with history and creating a time machine out a train in 1885. The guy's not that much of a genius. Neither is Zemeckis, but nobody was asking him to be. He just wanted to make a fun film about time travel. It's just that the time travel doesn't stand up to even a tiny bit of scrutiny. Prepare to have your head explode as you try and get it around the ten paradoxes that should break Back To The Future.