/ Dead Martys stacked all the way to the ceiling /
Near the very end of ”Back to the Future Part II (1989)” Marty has to get the sports almanac (Grays Sports Almanac: Complete Sports Statistics) back from Biff to stop the dystopian future from happening, future where Biff runs the whole place. He does this by using the hover board to slide along Biff’s car while he was driving. He manages to get the almanac from him but only when they are in a long tunnel. Then Biff tries to run him down as there is no where to escape from him and his massive vehicle; but, at the very last moment, Doc Brown drops a rope of fliers at the end of the tunnel which Marty grabs and is lifted away from Biff’s car into safety.
Now, the real question is how did Doc Brown know to drop that rope at that exact place and time?
If he was hovering over Marty and Biff for the first time, wouldn’t he just float to the other side of the tunnel and wait for them to exit, not knowing anything what was happening in detail, as it seems? How did he know Marty needed help there?
So, ”Back to the Future Part II (1989)” is the movie that most clearly demonstrates the dangers of time travel in general. With the simple act of buying a future sports almanac, Marty McFly accidentally creates a timeline where his dad is murdered, his creepy old best friend is insane and his mom suddenly looks like she’s starring in porn flick. This is made doubly uncomfortable due to the fact that his mom spent the entire previous film trying to have sex with him. Of course, all of this time-traveling horror takes a backseat to the part when Marty dies multiple times.
If you’re having difficulty remembering that scene, it’s because it never explicitly happens, but according to a theory we believe should be credited to Reddit user Hootinger, Marty originally got killed in the scene where he’s chased through a tunnel by Biff Tannen’s car, only to be saved by Doc Brown through the ”necromancing magic of time travel”. There’s actually more than enough subtle clues pointing in the direction of “Biff ran Marty down in the street like a stray dog for stealing his magic book” to make us wait in the car the next time a crazy old hermit kidnaps us through history. This theory actually fixes a plot hole in the movie.
During the climactic chase scene, Marty is about to disappear beneath the tires of Biff’s muscle car but is saved at the last minute by Doc Brown, who lowers a rope made of construction flags down from the flying DeLorean to carry Marty to safety. Biff, in turn, crashes into a truck full of shit, because shit is funny and Biff is a terrible person.
How Doc knew where, and when, to drop the rope?
He had no idea Marty was in trouble, and there’s no way he could’ve seen the chase while zooming around in the sky, because Biff was chasing Marty through a tunnel (more specifically, the tunnel to Toontown). The only logical explanation for Doc knowing exactly where to show up to save Marty is that he’s already seen it happen, meaning Marty has already been killed by Biff in an alternate timeline. Doc witnessed our plucky time-skipping hero get crushed like a denim grape beneath the wheels of Biff’s rapistmobile and then used the DeLorean to go back in time and prevent the tragedy from happening.
For all we know, what we see in the film isn’t the first time Marty has been killed.
Doc might be on his 176th Marty-rescuing attempt, which means ”Back To The Future” could be packed with dead Martys stacked all the way to the ceiling” and we would never know. Doc never tells Marty about all this, because why torture him with all that knowledge?
So, yeah… no one really wanted to see a ”Back To TheFuture” where Marty is emotionally crippled by the existential terror of his own mortality.