When a movie is edited, directors have to cut scenes out of the movie. Sometimes to cut down the movie's length, and sometimes for plot reasons. And can you believe that Robert Zemeckis was actually considering cutting one of my favorite scenes from Back to the Future?
Yes. That scene was going to be cut, but the audiences loved it so it was left in.
And here are some scenes from Back to the Future that never made it to the finished film:
Basically, in the scene, Marty tries to teach George how to say "no" to someone. But right when he does, a neighbor comes in and asks George if he could buy some peanut brittle. Then, in the next scene (which was in the finished film), we see George pouring the peanut brittle in a bowl. He offers some to Marty, but Marty looked at the peanut brittle with disgust and shook his head.
Doc's Personal Belongings
This scene takes place before Marty and Doc watch the tape from the Twin Pines Mall. Doc looks through his future suitcase and finds a bunch of stuff including a hairdryer, underwear, and a Playboy magazine.
Marty is at school, and he sees Lorraine cheating on her test. If you watch the scene, you'll see how obvious the cheating was. I'd be surprised if that wasn't why they cut it.
You may think you saw the Darth Vader scene. However, in the movie, the scene was only about 30 seconds long. The original scene was about three minutes long and was likely cut out for time because it feels too long this way. And this extended scene explains the continuity error in which the hairdryer Marty has in the original movie reappears and vanishes.
Got a Permit?
This is the scene after Marty writes the letter in the cafe. We see only part of this in the movie, and it ends after Marty places the letter in Doc's jacket. After that, Marty and Doc have a quick conversation and Marty says my favorite deleted line: "What if I go back to the future and end up being...gay?" Hysterical.
In this scene, George gets stuck in a phone booth when Biff's gang locks him in there.
* BONUS ROUND *
Back to the Futures II & III
In this scene, it is revealed that the old man who unintentionally gave Marty the idea to buy the almanac is Terry, the guy who charged Biff $300 for the damages done to his car in 1955. You might remember Biff and Terry from these two lines they exchange?
Biff: 300 bucks?! 300 bucks for a couple of dents?! Hey, that's bulls***, Terry!
Terry: No, Biff! It was horses***!
In 2015, technology had advanced to the point where you could watch six TV shows at once. In this scene, Marty tells his kids that when he was their age and he wanted to watch two shows at once, he had to put two sets next to each other. Same in 2016, Marty.
This scene is an extended version of the dinner scene where the McFlys are eating newly hydrated pizza. This scene was likely cut down because it was too long.
Old Biff Vanishes
In the finished film, after Biff changes the past, he appears to simply have a heart attack and falls to the ground. In this deleted scene, Biff actually vanishes into thin air. This scene was slightly gruesome for a family movie and director Zemeckis thought it was confusing enough to distract from the plot.
Burned Out High School
Mr. Strickland says at one point that the school burnt down six years before 1985. In this nineteen-second scene, we see Marty visit his burnt high school. But is it just me or does the high school look very fake?
Marty Meets Dave
In this scene, Marty discovers a drunken Dave outside Biff's casino. I feel like this scene was cut because they couldn't get Linda back for this movie and it would be strange for her to be excluded. If you read the comments, they mainly say two things: 1) Dave looks like Marv from Home Alone 2) The acting in this scene (by Marc McLure) was poor and he doesn't seem drunk.
The Tannen Gang Kill Marshall Strickland
In this scene, Marshall Strickland arrives to stop Buford from going into town and killing Marty. However, Buford shoots and kills him. This scene was cut because Buford killing him didn't fit into the family movie and this was the crime that Buford was originally going to be arrested for. However, they redubbed the line to robbing the Pine City Stage because Buford would likely have been hanged for this and he needed to stay alive so Biff would be alive in 1985.