The kiss heard round the space-time continuum.
- Marty is able to enter Doc's house without Doc there - and even though he broke in to the house in the past, there's no indication he broke in this time - indicating that Doc gave him a key.
- In fact, as he's entering you can see him place a key under the doormat. Doc told him where he keeps the spare key!
- Marty's steady relationship with Jennifer is one of the few stable parts of his life, even early on, and they clearly love one another.
- Just after George knocks Biff through the wringer, then kindly asks Lorraine if she's all right. It's just so cute.George: Are you okay?Lorraine: (silently nods)
- Even better, Marty, for the first time in his life, actually gets to see his dad kick ass for the first time in his life. The look on Marty's face says it all.
- All of this is preceded by George finally standing up for himself, something he couldn't even do in the original timeline's future.George: No, Biff. You leave her alone.
- What makes it so much better is that Biff bullies George all the time, and this time was no different, threatening to break his arm or not. George didn't even try to fight back, until Biff pushed Lorraine to the ground. Look at George's reaction to that, he sees it happen, he gets not just angry, but enraged, and whirls around, decking Biff in one hit. It's not that George hates Biff, it's that he didn't want Lorraine to get hurt.
- There's a subtle moment after the punch lands. At first, George is basking in the moment...but it only takes a second of him looking at Lorraine for his expression to soften, and he immediately asks if she's OK in a quiet voice. He's still the same lovable, kindhearted person that he was before the punch—all it did was unlock confidence to go with it.
- George and Lorraine's first kiss while "Earth Angel" plays, not only for what it meant for George and Lorraine, but also because it saved Marty and their other children at the very last second. After the kiss, George waves to Marty over Lorraine's shoulder, and Marty waves back, clearly glad to still have a hand to wave with.
- George's first attempt to talk to Lorraine starts out as hilariously goofy (read from visible notes: "I'm your density!... I mean, your destiny.") but when he corrects himself, she softly mouths "Ohh..." and gives him a cute smile. It probably was not enough to get her to go dancing with him, but she was taken by him there, just a bit.
- The text of Marty's warning letter to Doc.Marty: Dear Doctor Brown, on the night that I go back in time, you will be shot by terrorists. Please take whatever precautions are necessary to prevent this terrible disaster. Your friend, Marty.
- After Doc tears up the letter, insisting on not getting warned, Marty sits at the wheel of the DeLorean upset that he's not able to save Doc. Then it dawns on him "I got all the time I want, I got a time machine, I can just go back early and warn him!" and he changes the Return time to 1985 to ten minutes earlier. To hell with the space-time continuum, Marty's gonna save his friend.
- Too bad Marty returns to 1985 on the wrong side of town, and with the DeLorean zonked out by the trip back.
- Finding out that Doc really did use Marty's advice.Marty: What about all that talk...about screwing up future events? The space-time continuum?Doc: Well, I figured, what the hell.
- The fact that Doc went through the trouble of taping together Marty's letter, and kept it in his possession for all of thirty years (As evidenced by it now being brown and crinkled) is strangely moving, showing that in spite of his earlier objections just how much trust the Doc of the past had in his friend of the future, and decided that that was more than enough to overcome any doubts he had about the risk Marty had taken to save him.
- Marty's time spent bonding with Past George was surprisingly endearing.
- Look how excited George is in the cafeteria scene when he describes his stories to Marty; this is probably the first time in his life anyone has shown any interest in his work. Marty, for his part, is immediately charmed that he never knew his father was a creative person. Also leads to a brief moment of heartbreaking when George refuses to let Marty read his work, and Marty completely understands George's reasons for it.
- When Marty is struggling to open a bottle of soda, George takes the bottle from him and uses a nearby mailbox as a bottle-opener to pop the cap off. It’s kind of subtle, but George seemed to notice Marty’s struggle as they were talking and he didn’t step in until it was clear that Marty couldn’t get it open.
- It's not remarked upon, but Marty casually helping George with hanging laundry while giving him advice is incredibly endearing.
- This all culminates in George's goodbye line to Marty before the latter returns to the future: "Well, Marty, I want to thank you for all your good advice. I'll never forget it." And he doesn't.
- Before leaving, Marty tells George and Lorraine that being with them was "educational", as he learned that they weren't that different from him and he appreciates them more for that.
- When the Libyans arrive the first thing Doc says is "RUN FOR IT, MARTY!!!" and it's emphasized even further by the Last Words he says: "I'll draw their fire!" Despite how frightened he is (and let's face it, with good reason), Doc cares more about Marty than he does about himself, and is willing to sacrifice himself without a second thought to give his best friend a chance for survival.
- It's pretty heartwarming to see the Hidden Depths of future mayor Goldie Wilson. In 1985 he's been described as a bad guy simply because he wanted to replace the clock tower despite it being a major part of history. However in 1955 Marty himself sees that he was simply a good guy trying to make a difference. He even tries to advise George McFly to stand up to Biff during his first appearance. Despite not liking his job, he triumphantly marches with his mop in hand saying the following:Goldie Wilson: Mayor Goldie Wilson... I like the sound of that!
- Not to mention the sweet look on the face of the waitress behind Goldie as he proudly boasts his political aspirations to his boss. It's an easily missed moment, but she just stands there and smiles as he proclaims that one day he's going to be somebody important. Who out there wants to bet that she voted for him?
- Goldie Wilson's story reflects changing racial attitudes after the Civil Rights Movement. In the 50s, the idea of an African-American man like Wilson being mayor is treated like a pipe dream; in the 80s, it's more of a mundane reality.
- Jennifer writing "I love you!" next to her grandma's phone number for Marty.
- And before this, the two of them are walking and discussing the possibility of Marty sending his demo tape to a record company (which Jennifer is 100% supportive of while Marty doesn't have that much confidence about his talents), when Marty is distracted by two attractive women walking by. Instead of getting pissed and going into Clingy Jealous Girl mode, Jennifer just nonchalantly turns Marty's head towards her and continues the conversation. They then carry on and are shown playfully flirting as if nothing happened. It's small, but it speaks volumes of what kind of relationship the two of them must have, and how close they must be.
- Also, as Marty complains about his parents, who we haven't met yet, Jennifer tries to tell him that they mean well, which Marty realizes after spending time with them in 1955.
- And if you look carefully in Marty's room, you can see he has a big framed photo of Jennifer on the shelf above his bed. D'awww.
- Finally, when Marty is trying to explain to 1955 Doc why it's so important that he gets back to the future, he tells him that "I got a life back in 1985; I got a girl!" and shows Doc the love note Jennifer wrote on the flyer.
- 1955 Doc's triumphant yell when he sees the DeLorean go back to the future. Part of that was definitely it finally sinking in that he finally made something that worked.
- Even before that, after Doc gets over his Oh, Crap! moment of realizing the power cord is unplugged, jeopardizing Marty's time jump, he gets this look of determination on his face - no matter what, he WILL get Marty back to his right time. His unrestrained joy at pulling it off seals the moment.
- Relating to this, when Doc and Marty first meet in 1955, the latter tells Doc the story of how he came up with the flux capacitor as proof that he really is from the future. Doc then goes with him to where the DeLorean is hidden, and shows him a picture he drew of the flux capacitor. Marty then reaches into the car and switches on the real thing. Doc's gleeful "IT WORKS! I FINALLY INVENTED SOMETHING THAT WORKS!" is a sight to behold.
- And what does Doc do when he finds out he invented (or will invent) a working time machine? He doesn't even consider using it for personal gain. Instead, his first thought after realizing it works is to get it back to the lab so they can get straight to work on getting Marty home.
- Marty telling 1955 Lorraine that she might regret drinking later in life. Remember that 1985 Lorraine is a bloated alcoholic due to her unsatisfactory marriage. Marty was trying to save her that fate by discouraging her drinking before it got out of hand.
- The Johnny B Goode rendition has elements of this, seeing how much fun the kids are having as they're exposed to rock and roll a little earlier than they might have been in the old timeline, and have fun dancing, while Marty is getting to play the kind of music he likes for an enraptured audience and the band members are grinning themselves over getting to play this.
- During the song, a few of the other students pass by George and praise him for knocking out Biff, with one girl telling him that he should consider running for class president. Considering that George was the school's biggest nerd who was bullied at worst and ignored at best, seeing him getting the respect of his peers is surprisingly sweet.
- George and Lorraine's relationship in the altered timeline, still playfully bantering and flirting with each other like they were teenagers. After being together for 30 years, it's quite clear that they are still very much in love.
- When Jennifer pays Marty a visit and they embrace, he looks to the front door to see his parents watching them through the screen door and smiling warmly, before leaving them to their privacy.
- Doc's return to 1985 at the end. He didn't come by just to say hi or anything, he came by because he found out something horrible will happen to his best friend's future family and he wants to set it right.
- When Marty and Doc are shaking hands at the end before Doc finally goes to the future, you can just feel how much they care about each other. Marty's just saved his life, and Doc is just staring at him with this look that says "thank you."
- Doc also seems to be a lot calmer in this timeline, and for plenty of good reason: not only does he have the self-confidence that he made something that works and can be used for the greater good, Marty using it to save his life made him less paranoid about knowing too much about the future.
- 1955 Doc telling Marty that he's sad about the latter returning to the future and that it's going to be difficult waiting 30 years before they can talk about the past week's events to each other.
- The cherry on top of Marty's 1985 life after altering the timeline is seeing the new Toyota 4x4 he desperately wanted at the beginning of the movie, now under his possession, in the garage, accompanied by the moving Alan Silvestri score. Marty is driven to speechlessness at the sight of the truck. The same scene starts off Part II on a heartwarming note as well.
- Even better is Jennifer showing up as Marty's admiring the truck. After all he's been through, she's the thing he wanted to see the most. Even if it was for a moment, Marty's life was perfect.
Jennifer: How about a ride, mister?Marty: Jennifer... Oh, you're a sight for sore eyes. - Marty being protective of his parents throughout the film even when it could endanger his existence, such as protecting his mom from Biff in the cafeteria and stopping him from hurting his dad at the diner. Made even better by the fact that Marty has had to watch Biff bully his dad his whole life, and could never do anything about it before.
- Even Biff gets a moment at the end. When the finished copies of George's first published novel are delivered to the McFly house, Biff excitedly brings them inside and actually seems genuinely happy for his old enemy. He even says hi to Marty as he comes in!
- How much does Einstein trust and love Doc? He sits in a car, on his own, with the door closed, while the car is driving itself, and seems entirely unconcerned on the other end when he returns; Doc subsequently gives him scratches. That is true love.
- In a weird way, the moment when Lorraine finally kisses Marty but pulls back, not understanding why it feels "wrong" and only able to say that it's like kissing "her brother." She recognizes a powerful familial connection between them without having the context to pinpoint that he's her son.Marty: Believe me, it makes perfect sense.
