Directed by: Robert Zemeckis
Starring: Christopher Lloyd, Michael J. Fox, Mary Steenburgen, Lea Thompson, Thomas F. Wilson, Elizabeth Shue
Other mistake: When the movie ends and Doc says, "It means your future hasn't been written yet," watch his son Verne behind. He looks towards the camera and seems unhappy, makes a beckoning gesture (presumably at the crew), and points at his crotch. Seemingly, the kid was having a hard time trying not to pee on himself. (01:50:39)
Other mistake: When Marty returns to 1985 from 1885 the time machine is destroyed by a train. What is strange is that not only does the train not stop (which is mandatory in the event of an accident) but there is also no reaction from people nearby, such as those in the vehicles waiting to cross the track at the level crossing. Later, when Marty returns to the site with Jennifer, there is still no sign of police officers or other officials.
Marty McFly: Hey, Doc! Where you goin' now? Back to the future?
Doc: Nope. Already been there.
Trivia: "Mad Dog" Tannen's actions after shooting Marty are a perfect homage by Thomas F Wilson to Lee Marvin in "The Man Who Shot Liberty Valance." He even gets the facial expressions, the mumbled and sarcastic thanks and the jaunty angle with which he holds the gun right.
Answer: He simply has an absurdly low tolerance for alcohol, and whiskey is not a wise choice if this is the case. It helps set up the joke when Marty asks the bartender, "How many has he had?", and he replies by telling Marty, "Just the one", as we are meant to think Doc has been in the bar all night drinking away his sorrows.
Jazetopher