Deliberate mistake: When Old Biff and Young Biff are sitting in Biff's car, the car's rear-view mirror vanishes during all shots of Old and Young Biffs together. Presumably this made the split-screen effect easier to do.
Back to the Future Part II (1989)
1 deliberate mistake - chronological order
Directed by: Robert Zemeckis
Starring: Christopher Lloyd, Michael J. Fox, Lea Thompson, Thomas F. Wilson, Elizabeth Shue
Revealing mistake: In the scene where Doc Brown is following Biff into the tunnel, as Marty starts to pass between the cars on his hoverboard, one of the wheels on the rig supporting the hovering DeLorean is visible. (01:30:30)
Biff: Look, Lorraine, you walk out that door and I won't only cut off you, I'll cut off your kids.
Lorraine: You wouldn't!?
Biff: Oh, wouldn't I? First your daughter, Linda. I'll cancel all her credit cards. She can settle her debts with the bank all by herself. Your idiot son, Dave. I'll get his probation revoked. And as for Marty. Well, maybe you liked to have all three of your kids behind bars just like your brother Joey. One big happy jailbird family.
More trivia for Back to the Future Part II
More questions & answers from Back to the Future Part II
Answer: At the end of the first film, Doc says, "what the hell" in response to the letter Marty gave him. So this shows it is not that strong a conviction, especially in the face of definite knowledge about something bad happening. It is also a way for Doc to repay Marty.
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