Biff: Why don't you make like a tree, and get out of here?

Marty: Doc look, all we need is a little plutonium!

Doc: Oh! I'm sure that in 1985, plutonium is available at every corner drug store, but in 1955 it's a little hard to come by. Marty, I'm sorry, but I'm afraid you're stuck here.

Doc Brown: Now, if my calculations are correct, when this baby hits eighty-eight miles per hour, you're gonna see some serious shit.

Doc: Roads? Where we're going we don't need roads.

Doc: There's that word again, 'heavy'. Why are things so heavy in the future? Is there a problem with the earth's gravitational pull?