In the Biff Tannen version of 1985, Marty comes across a TV extolling the virtues of Biff Tannen, and how he rose to power and fame. In this film, it talks all about his family’s start, which begins with Mad Dog Tannin in 1885.
This foreshadows Mad Dog Tannen’s appearance as the bad guy in “Back to the Future Part III”, and is actually the first time in the series that we see Mad Dog as he actually is, not just on shirts or in video games.
When old Biff arrives in 1955 to give his younger self the Almanac, he's wincing in pain. Most people assume it's from the DeLorean's shocking ride, but it's actually supposed to be because he's fading away like Marty almost did in the first film.
He's going back to change his own future, which eliminates his own timeline. The rest of the shots of his suffering were cut. Pretty gruesome, now that we think about it – but it takes some time for him to disappear entirely, which allows him to get back to his own time and save himself. We think.
He Makes His Own Time
When Marty finally gets back to 1985, he finds the world turned on its head, with Biff Tannen in control. Biff has killed George McFly, married Lorraine, and amassed endless wealth thanks to the Almanac his elder self came back to give him.
His Hill Valley is completely different, and it's best seen by his decision to get rid of the city hall clock tower. It's the only version of the town seen in all three films with no clock tower. The filmmakers went this route with the Biff timeline on purpose, in order to contrast Marty's effect on Hill Valley as opposed to Biff's.
Stopped Off in 1989 on His Way to Mount Doom
Remember the befuddled video game player that Marty schools in the ways of video-game zapping in 2015? None other than Elijah Wood in his very first role!
You can just barely see the young man who will grow up to become the famous hobbit of the "Lord of the Rings" series. He was already on his way to acting with the best of them back in 1989. Wood's credentials were set from the start – hard to do better than having your first appearance in the "Back to the Future" films.
Due to contractual problems, Crispin Glover decided that he wouldn't appear in either of the "Back to the Future" sequels. It forced the filmmakers to figure out how to do things when they couldn't use one of their principal actors, especially since Marty once again travels to 1955.
It all culminated in a lawsuit against the producers because they reused shots for the first film in the second and third without Glover's expressed or written consent. Glover won his lawsuit, and because of the landmark case, it became illegal for studios to use someone's likeness without their consent.