Directed by: Robert Zemeckis
Starring: Christopher Lloyd, Michael J. Fox, Mary Steenburgen, Lea Thompson, Thomas F. Wilson, Elizabeth Shue
Audio problem: When the very first song ends during the Festival scene, keep an eye on the guitarist to the right. His hand is still moving but no sound is coming out of his guitar. (00:56:55)
Audio problem: When Mad-dog Tannen is standing over Marty, who is playing possum, you see Tannen cock his gun twice between two shots, although there is no sound effect for the first time. (01:27:50)
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.
Trivia: When filming the scene where Marty is being hanged from the clock tower, Michael J Fox agreed to really hang from the rope. Whilst filming, Fox held the rope away from his throat with his hand. At one time he wasn't holding the rope and was really being strangled. The film crew didn't realise, they just thought it was really good acting, until he passed out.
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