Setup and payoff is a technique used in storytelling, particular in humor, in which a seemingly irrelevant detail or statement is "set up" early in the story, and has an importance that becomes very clear later (i.e. "pays off") later. Back to the Future was praised as a film so tightly written that not a single line of dialogue has been wasted. Writers Bob Gale and Robert Zemeckis employed the technique in the other parts of the trilogy, even to the extent of setting up a sequence in one film and having the payoff come later. One of the more visible examples began in Back to the Future Part II, when Jennifer Parker is in 2015 and hears an elderly Lorraine Baines McFly talk about how Marty's life was ruined by "the accident with the Rolls-Royce". Fans waited six months to see the payoff in Back to the Future Part III, as Marty decides not to race against his friend, watches the outcome, and tells Jennifer "I would have hit that Rolls-Royce!".
Even before Marty and Doc are seen or heard, framed newspaper clippings show that Doc Brown once had a mansion and a large tract of land that were gone by 1985, but which Marty will see when he goes back to 1955; a dog food dish establishes that there is a dog named "Einstein"; a radio broadcasts a commercial for Statler Toyota (the payoff being that in 1955, it was Statler Studebaker), and a television newscaster describes missing plutonium (paid off a minute later when Marty's skateboard bumps into the box of plutonium) and the Libyans (seen later at the Twin Pines Mall) who claimed responsibility for the theft. In the first minute of his arrival at Doc's house, Marty brings a skateboard and hooks up a guitar to an amplifier, demonstrating that he has skills that he will use later.
An early example occurred in the Back to the Future: The Game Episode 1 "It's About Time" where Marty has a dream of the world's first temporal displacement, which played out differently than he remembered. At first it seems like the dream is merely to foreshadow Marty finding Doc's notebook, but it also foreshadowed Doc and Einstein's disappearance at the end of "Get Tannen!".