So here's the deal: some Charlie Chaplin mega-fan was watching Chaplin's 1928 film "The Circus" one day when he caught a glimpse of something that made him do a double take. He rewound the film and watched the scene again. Then again. And again.
What did he see? Well, he saw someone walking through the shot talking on a cell phone. In 1928. I repeat: A CELL PHONE. In 1928. Yes indeedy. His conclusion: time traveler.
Of course! It's so obvious.
You can see the clip from the film below (Note: There is no sound, so don't freak out and think your speakers are broken.)
Now, what I want to know, is where are Doc and Marty?