Character mistake: At the beginning of the movie Marty is turning on a huge guitar amplifier. The two switches for the filaments are misspelled. They are shown as "filiment." (00:03:25)
Character mistake: Before playing Johnny B Goode Marty says it's a blues riff in B, but then plays the song in B-flat.
Character mistake: In the parking lot when Marty begins to film, Doc says the date and exact time according to his watch. Marty then looks at his watch. Apparently his is off because he shakes his wrist and puts the watch to his ear to see if it is still working. However, he is wearing a digital watch which wouldn't tick or likely have broken parts to rattle.
Answer: It's a way of saying "scram" or "get lost." But Biff is so dim, he doesn't realize he's saying it wrong; the expression is "make like a tree and leaf", with the joke being that "leaf" is meant to sound like "leave."
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