When old biff and young biff are in the garage, after old biff hands young biff the book, and young biff makes the joke about "make like a tree and get out of here" and thenold biff slaps the back of his head and corrects the joke, young biff throws the book in the back seat and say "alright then leave!" Then all of a sudden old biff has the book in his hand!!!!! Its at 1:08:54