Doc Brown, the legendary scientist played by Christopher Lloyd in Back to the Future, he could have financed his experiments illegally. This was revealed by Bob Gale, screenwriter of the trilogy together with Robert Zemeckis, during a recent chat with the Russo brothers.
"As we were writing the story of the character, we asked ourselves what his backstory was, how he could have invented the journey through time? It is very far from the clichés of the scientist, or even the mad scientist at the time. First of all it's a kind of rebel and hero, because he steals plutonium from terrorists. It is very cool. We see all these things in the laboratory and we can't wait to meet him " Gale explained during an episode of Russo Bros. Pizza Film School, the live show organized by the directors of Avengers: Endgame to talk about the films that have influenced their career.
Speaking of the character's past, the screenwriter later revealed that Doc may have funded his time travel experiments through an insurance scam: "But there are many other things. Some of which you don't understand before having seen the film for the second or third time. The newspaper you see in the opening scene: it was Doc Brown who set fire to his house to get the insurance money and continue to finance your experiments? "
For more insights, we refer you to the details on the original Back to the Future ending and to the crazy theory about Eric Stoltz.