Primer (2004)

The Original: Shane Carruth's ultra low-budget sci-fi tale follows two engineers, Aaron (Carruth) and Abe (David Sullivan), who accidentally create a machine that allows an object - or a person - to travel back in time.

The pair start out by cheating the stock market, but eventually crack and decide to alter their own lives for the better.

Soon, paradoxes are springing up everywhere and the two friends quickly fall out.

With Added Doc Brown: Doc sees the lads as kindred spirits and decides to help them out by "fixing" their device to allow travel into the future.

Unfortunately, he hasn't counted on the fact that they're both ethically-challenged idiots who quickly use their machine's new-found power to journey far into the future.

Risk To The Space/Time Continuum: Earth itself is eventually swallowed by a giant time vortex created when the two men go forward in time and get into an argument about who married the hottest swimsuit model.

Vanishing into a parallel universe, Doc swears that he'll stick to helping likeable scruffpots with no scientific training in future.

Next: The Butterfly Effect