In Back to the Future III, Marty & Jennifer see Doc Brown & his family in a steam locomotive replete with a flux capacitor. How does Doc create it?
In Back to the Future Part III, Marty McFly (Michael J. Fox) travels to September 2, 1885, to save Doc Emmett Brown (Christopher Lloyd), who is purportedly killed by Biff Tannen’s (Thomas F. Wilson) great-grandfather. After the DeLorean is unable to reach 88mph for it to be able to travel back in time, Doc devises a plan to use a steam locomotive to push the DeLorean up to the requisite speed. During this endeavor, Doc encounters Clara Clayton (Mary Steenburgen), who is later seen accompanying him in the…