That movie used to make me cry. Probably still would, if I ever watched it again.

In the original script, the time machine was a refrigerator. They get Marty home by sneaking him (in the fridge) into a mock-up house, in a mock-up city, in an atom bomb test zone right before the countdown. Somehow it powers the fridge instead of vaporizing it. Even more ridiculous; slightly more subversive.