1. In the opening credits, there's a clock that foreshadows the movie's dramatic climax.
2. Marty auditions for the school dance by playing "The Power of Love" by Huey Lewis and The News. The judge who tells him he's “just too darn loud” is none other than Huey Lewis.
3. Marty, who plays the guitar, has guitar picks mixed in with his pocket change.
4. Marty first goes back in time in the parking lot of the *Twin Pines* Mall. Upon arriving in the past, he runs over a pine tree. When he returns to the present day later on in the movie, the name of the mall is changed to the "Lone Pine Mall."
5. Towards the end of the movie, the Delorean, driven by Marty, disappears just short of a movie theater that's playing The Atomic Kid — the Delorean is nuclear powered.
6. At the end of the movie, Marty wakes up in the exact same position he was sleeping in earlier on in the movie — with the same clothes and sheets, as well. He looks around and says "what a nightmare," assuming it was all just a dream.
7. In Part II, a movie theater marquee spotted in the background is advertising Jaws 19. If you look closely, you'll see it's directed by Max Spielberg — that's Steven Spielberg's actual son.
8. When Marty goes to a cafe in 2015, the price of everything is inflated. A Pepsi, for example, costs two dollars — almost four times as much as the 1985 price.
9. The ledge that Doc broke on the clocktower in Part I is still broken in Part II.
10. In the alternate timeline, Richard Nixon is running for a 5th term as President and the Vietnam War is ongoing.
11. And a 2015 newspaper mentions "Queen Diana" and a female US President.
12. In Part II, the pattern on Doc's shirt depicts riders on horseback chasing a train, which foreshadows the setting for Part III.
13. In Part I, Doc says he came up with the idea for the flux capacitor after he slipped off a toilet trying to hang a clock, causing him to hit his head on the sink. In Part III, we get a glimpse of that very clock and toilet.
14. Doc's bandana in Part III (right) is made from that very same shirt from Part II (left) that foreshadowed the film's setting.
15. The local musicians depicted in this scene are played by the actual members of ZZ Top. At one point, they even spin their instruments, a signature move the band is known for — and Marty notices.
16. The Statler family, referenced only in these background shots, have cornered the market on "vehicle" sales in Hill Valley, California, for at least a century.
17. Speaking of local businesses, Biff Tannen crashes into a "D. Jones Manure Hauling" truck in Part I. In Part III, "Mad Dog" Tannen falls into an "A. Jones Manure Hauling" cart.
