The Time Machine (1960)
The Original: Our hero, H George Wells (Rod Taylor) fashions a time machine, which looks like a brass factory had sex with an umbrella.
He goes off into the future, where he discovers that two races - the peace-loving Eloi and the vicious, meat-eating Morlocks - are all that is left of the human race.
With Added Doc Brown: Wanting to help Wells' later quest to rebuild society, Doc arrives in the flying Delorean carrying a thousand books crammed into his iPod.
Sadly, he lands on several of the Eloi and the rest start worshipping him as God.
Risk To The Space/Time Continuum: When Wells orders Brown to go "the ruddy damned well away" a shaken Emmett takes off again in the car.
But a Morlock has snuck aboard the vehicle and, in the ensuing struggle, the Delorean is sent back to the dawn of the human race.
In some parallel universe, the entire human race is now Morlocks. Almost everything is different, though the Daily Mail is still published.
Next: Time After Time