Flying Spaghetti Monster wrote:
Of course this movie probably has more questions raised about its plot than any other film in cinema history, but mine is simple.
Doc and Marty learn that Biff went back to November 5, 1955, so they go back to an early morning time on that day, hoping to arrive first. They hide the DeLorean behind the billboard.
But if memory serves, isn't the other DeLorean there at that same spot already, or won't it be there by the time dawn comes around, because the Marty from the first film needs a place to hide until he and Doc can get it later the next night to bring it back to the laboratory?
On that side of the screen: One could infer that a universe-annihilating paradox would occur if two DeLoreans were in the same place at the same time.
On this side of the screen: It's pure movie fun (or supposed to be, anyway). It doesn't have to make sense.