First Installment Wins: The first is iconic. The second and third are good, but definitely not remembered like number one.
Hilarious in Hindsight: Robert Zemeckis and Steven Spielberg's first concept for the time machine was not a DeLorean. Originally, the idea was that it would be a highly-scientific laser array that sent Marty back to the past. To get him back to the future, Doc Brown originally was going to put him in a refrigerator during an A-Bomb test. Spielberg vetoed the concept back then out of fear that kids would climb into abandoned refrigerators and become trapped, not to mention it was incredibly expensive. A couple of decades later, however...
Rewatch Bonus: Parts II and III make greater sense when watched back-to-back, as you'll see signs of Foreshadowing and other details between the two parts. For instance, as Doc and Marty discuss their plan at the train station, you'll see that Clara Clayton was standing in the background waiting for someone to pick her up.
Some Anvils Need to Be Dropped: The "Don't let your pride get the best of you" aesop they drill into your head in Parts 2 and 3. It's Anvilicious, but it is surprising how many people actually do put themselves into situations just to prove themselves to others.
Vindicated by History: The sheer number of jokes about the approach and arrival of the year 2015 has definitely increased the notability of Part 2. This leaves Part 3 as the only one that isn't really iconic.
What Do You Mean, It's for Kids?: Remember the joy of watching these films when you were a kid? Remember the scene where the second lead is gunned down by Libyan terrorists? They sure don't make 'em like they used to. On the other hand, when Marty found himself in 1955, he made it a point to try and save Doc from his future fate... and succeeds; it was more of an extremely delayed Disney Death. There's also Marty's plan to get George and Lorraine together at the dance involved him faking a rape attempt on his own mother, which was then broken up by a real rape attempt from Biff. It is generally believed that the movie most definitely would've received a PG-13 rating had it been released today, much like another Zemeckis film that came out later in the decade.
"If my calculations are correct, when this baby hits 88 miles per hour, you're gonna see some serious shit!"
The first sequel isn't much better, starting with a Groin Attack on Marty Junior. Of course, the cherry on top is the alternate 1985 where Biff is a Corrupt Corporate Executive who murdered George in cold blood, forced Lorraine into marriage and breast implants, sits in a jacuzzi with naked women, and has turned Hill Valley into a hellhole.
Part III has Buford hanging Marty, threatening Clara with rape, and attempting a slow death by bullet on Doc. Plus there's Doc's (implied) one night stand with Clara.
Amusingly, this trope was why Disney turned down the first film, as they thought it was too raunchy, whereas many other studios thought it wasn't raunchy enough (this was the era of teen sex comedies like Porky's and Revenge of the Nerds).
Angst? What Angst?: Marty's mother pretty much shrugs off her Attempted Rape, and the fact that the man who attempted to rape her is working for the family thirty years later doesn't seem to cause her any noticeable distress.
Broken Base: Some fans take issue with the ending playing up the family's new possessions too much, saying it gives a very materialistic message.
Before he was going to travel 25 years into the future by himself, Doc mentions that he'd get to find out who'd win the next 25 World Series. Then in Part II, we see the horrific results of someone using future sports knowledge.
Plus, going ahead 25 years would put him smack in the middle of the US recession. Not exactly a time to visit to give you optimism for the future.
Genius Bonus: Biff's goons are very intimidated by the Starlighters, saying "We don't want to mess with no reefer addicts." To many viewers, knowing that marijuana is not addictive and does not cause violent behavior, this may make them seem like cowards. Those familiar with the time period, though, will know that it was the era of Reefer Madness and the goons had just bought into the propaganda. May double as a Parental Bonus.
The angry Libyan terrorists shooting Doc Brown are less funny after the West Berlin disco bombing of 1986 and the bombing of Pan-Am flight 103 in 1989, both committed directly by or on orders of the Libyan government.
At the start of the movie, a newspaper clipping is visible indicating that Doc Brown's mansion from the 50's burned down and he wound up selling the land to developers. In 2008, Christopher Lloyd's home in California, which he was selling at the time, burned down in the Tea Fire.
In the "Making Of" documentary, Michael J. Fox expresses interest in travelling back in time to become a cowboy. Then, in Part III, he really does. He even lampshades this in the behind-the-scenes special for Part III.
Doc says his DeLorean is electrically powered. In canon, this is nonsense because you can clearly hear an internal combustion engine which sometimes fails to start up. The need for gasoline becomes a plot point in the third movie. Fast forward to October 2011 when the DeLorean Motor Company announces the DMCEV which actually is electrically powered. It runs on batteries instead of a 1.21GW nuclear reactor, though.
Doc was talking about the time travel equipment, not the normal functionality of the car. Given what happened in Part III, he probably should have had an electric engine put in in the future.
The shopping mall in pre-time travel 1985 is named the Twin Pines Mall.
Hollywood Homely: Marty's older sister Linda in the original 1985. Though not a model by any means, she's relatively cute and certainly not somebody you'd expect to have too much trouble finding a boyfriend.
Narm Charm: Okay so Marty almost fading has some bad green-screening, but it's still tense and terrifying to see him almost fade out of existence.
Sacred Cow: Regardless of people's opinions of the later movies, the first is widely regarded as one of the best time travel movies of all time.
Turns out, the image of the future Part II portrays stuck around in everyone's minds. The real-life 10/21/2015 ended up being something of a celebration of the series and The Future.
Sleeper Hit: No one expected the movie to become as big as it did. Robert Zemeckis openly admitted he was just hoping it would break even and the final bit with the Delorean flying and "something's got to be done about your kids!" was meant as a joke on Marty having just changed the past for his parents. Michael J. Fox recalled his agent telling him that the movie was a hit and he was pleased, but the agent had to reiterate that it was a BIG hit.
Special Effect Failure: The Bobs were never thrilled with the effect used to show Marty's hand fading from existence.
Also, the green-screen shots of the flame trails not burning Doc and Marty are pretty obvious nowadays.
Squick: Behind the scenes: the idea that every studio except Fox and Disney thought that this film, which features a boy's mother falling in love with her son, was not risque enough.
Strawman Has a Point (or Jerkass Has a Point?): Barely, since it relies on a coincidence Strickland couldn't have known about. He might be something of a jerkass to Marty at the beginning of the film when claiming he's a slacker who'll never amount to anything, but he is right that Doc Brown is dangerous, in a way - given he's not only willing to perform risky and highly illegal time travel experiments powered by stolen plutonium, but to rip off terrorists for said plutonium who might be out for revenge, and to allow Marty to be dragged into the situation.
The 2010 HD transfer used on the Blu-ray and re-released DVD. (Like Digital Destruction, too, but minus the "digital" part.) The end credits are totally messed up: three-fourths the width they should be, way off-center, and listing to the left. It's as if the scanner was bumped out of alignment and something tried to autocorrect it without any human noticing. Those who recall Parts II and III getting misframed DVDs in 2002 may be wondering if Universal Studios Home Entertainment can get anything right; however, unlike that case, they're not fixing anything, and refuse to admit it's even wrong. The 2015 re-releases provided an opportune moment for Universal to fix this, and also improve the picture quality of the main features even further, but they instead just repackaged 2010 discs in new cases.
Because of the Rule of Funny, Marty asks for a Tab followed by a Pepsi Free, looking for something sugar-free. The problem: Pepsi Free was caffeine-free, not sugar-free.
Values Dissonance: In the DVD commentary, it's mentioned that some European audiences were put off by how the "improved" McFly family had become more materialistic, as exemplified by Marty getting the truck seen earlier in the film.
Also to modern audiences, the implication that Chuck Berry was inspired to write his most famous song by hearing a white kid play it (Berry was an established, popular musician with a history of hit records years before "Johnny B. Goode" was released).
The fact that the film, a mainstream, widely-popular and heavily beloved/referenced movie, involves incest not only as a major plot point, but Played for Laughs, could also count.
The Woobie: George, before he Took a Level in Badass. The poor guy has been getting pushed around by Biff his whole life. He's always unsure of himself and ready to give up his ambitions because he can't stand even the thought of rejection.
Accidental Aesop: The ending of Episode 5 is sort of the logical conclusion to the entire series and films. Screwing around with the timeline keeps fucking things up til you have three older Marty's begging young Marty for help, all from different timelines. At that point, Doc just shrugs and tells Marty to ignore them. Now is important.
It's actually brought up several times throughout all five episodes.
Broken Base: There is a certain friction that occurs between those who are longtime fans of the Back to the Future franchise and those who are longtime fans of the Telltale Games company.
Fanon Discontinuity: To main die-hard fans of the original trilogy, this game might as well not exist. Less die-hard fans are fine with it, though. Being an example of No Problem with Licensed Games (and getting many of the original actors back) really helps. It's also the first thing in the series to really utilize Jennifer as a character, and both Edna and Trixie serve to balance out the series' mostly male-dominated cast.
Telltale has stated that the game doesn't necessarily have to be considered canon.
Jerkass Woobie: Even after everything, it's hard not to feel kinda bad for 1931!Edna when Marty breaks her up with Emmett.
Just Here for the Plot: Many non-gamers have taken interest in the game strictly for the Back to the Future story line — much to the chagrin of the more avid gamers who are, overall, disappointed with the game play of the series.
The Scrappy: Edna Strickland, though this is intentional.
The Woobie: The Citizen Brown timeline in Episode 3. Everyone seems on the verge of a nervous crackup due to the Dystopia of alternate Hill Valley, Marty seems like he's panicking about 86% of the time, and the only halfway normal person is a Delinquent who would probably be a child psychologist's field day. Even Brown himself comes off as a Tragic Hero.