Fans of the movie will be interesting to read about the standard theory is not the plot of our favorite movies.
And really, because we can not quite correctly perceive what is on the screen?
Let us think about it.
"Back to the Future". Doc - suicide
Doc is ready to kill himself along with Marty at the parking lot during their first time travel. Moreover, he did not test the time machine, he admits that many of his inventions was a failure.
So, at the moment of truth, when it is ready to find out if his life's work a great success or a complete failure, it not only leads DeLorean toward you, but enough of March, when he tries to escape.
If the test of the time machine has ruined, both of them would be killed. It is this desperate and wanted to dock in the event of the failure of the experiment.
Why Skynet does not destroy humanity?