The very beginning, where you hear the prayers of the town, proving that the movie is one long heartwarming parade from beginning to end:
Mr. Gower: I owe everything to George Bailey. Help him, dear Father.
Martini: Joseph, Jesus, and Mary, help my friend Mr. Bailey.
Ma Bailey: Help my son George tonight.
Bert: He never thinks about himself, God, that's why he's in trouble.
Ernie: George is a good guy. Give him a break, God.
Mary: I love him, dear Lord. Watch over him tonight.
Zuzu: Please, God. Something's wrong with Daddy. Please bring Daddy home.
Plus the fact that God not only hears those prayers, but is already working on the problem.
Mary, seeing her husband trying to keep a group of desperate customers from selling out to Potter (and only moments ago having begged him to let things be and continue to their honeymoon), is the one to first offer their honeymoon fund as loan capital to help the customers survive until the bank re-opens.
And the distribution of the funds had a follow up moment. Except for the Jerk Ass who went first demanding his full amount, most of them accepted twenty dollars a piece. And then one lady says "Can I just have $17.50?"
If you noticed, when George started using his honeymoon money to cover the run on the B&L, Uncle Billy and the two cousins start to open their wallets as well. Just George and Mary's money wouldn't have covered it.
Mary: Remember the night we broke the windows in this old house? This is what I wished for.
What makes this even more touching is the setting. The happy couple are in a leaky old house with a record playing, when they had planned to take a deluxe honeymoon out of town. But Mary is happy... because she's with the man she loves.
In the same scene, you see that Mary isn't the only person helping set up this honeymoon. Ernie and Bert are there, too. And once the record stops playing, Ernie and Bert stand out in the rain, singing through the window, to keep up the mood. It really shows how important George is to everyone, and how far people in the tower are willing to go to help him.
The denouement when George Bailey finally realizes that he has gained far more than he lost for staying in Bedford Falls, especially when seemingly the entire town comes to help him after Mr. Potter claimed that they would hate him for losing their money.
When George is on the bridge crying out, "I want to live again," pay attention to what happens. He's calling out to Clarence, his guardian angel, and nothing happens. Then he breaks down and whimpers, "Please, God, let me live again"... and immediately the wind dies down and it starts to snow, showing that his prayers have indeed been answered and things have finally changed back to the way they're supposed to be.
Notice, too, that once George is back in the normal world, his mouth is bleeding again and he's got Zuzu's petals in his pocket... but no mention is made of his bad ear. It's at least a possibility that George was given his hearing back permanently as an extra "Christmas gift" and reward for his renewed faith.
Am I weird to think the scene where George is getting drunk in the bar and Mr. Welch punches him out, and Martini and Nick are so nice and concerned about him is heartwarming?
You are not alone in thinking that. It seems so out of character of George to act this way so Nick and Martini are moved by the sight of their poor friend.
It's not just Martini and Nick. When George is punched, almost the entire bar gets up to make sure he's alright.
Fridge Brilliance: That was the answer to his prayer: he had just begged God to show him the way out of his predicament, and immediately his friends show up to offer help and concern. George was just too depressed to notice.
For me, it's the scene where George is at the dinner table with his dad. Especially with what happens later that night. In a lot of fiction, if a character is killed off, the main character sometimes gets into a huge argument ("The last thing I said to him/her was that I wished I wasn't his son"), but George's comment? "Y'know, Dad, I think you're a really great guy." Just a brief moment of peace between father and son.
And then George's oldest son is named Peter, after his dad. Their relationship wasn't onscreen much, but it's clear just how much they loved each other.
Earlier in the scene, George and Harry carry their mother in and deposit her in her husband's lap, telling their father they have a present for him, and the senior Baileys hug and otherwise display the kind of comfortable affection any couple would want to have after so long together.
Mary and the children are watching George flip out in ways that terrify them. But when they recover their ability to speak, their first thought is, "We'd better pray for Daddy right away, so he'll feel better." Heartwarming for this troper.
It's very easy to miss at first, but Mister Gower manages to come back from his drunken despair and becomes a much better man and a dear friend to George. It's a stark contrast to both how he was in the start of the movie and in the Pottersville reality.
As awful as Pottersville is, there is something nice about the fact that Bert the cop and Ernie the cab driver are still friends, regardless.
George: I wanna live again! I wanna live again! I wanna live again... Please, God... let me live again.
The sheer, unrestrained joy that overcomes George when he realizes he's back.
George: My mouth's bleedin', Bert! MY MOUTH'S BLEED-... Zuzu's petals... Zuzu... THERE THEY ARE! BERT! WHAT DO YOU KNOW ABOUT THAT?!! MERRY CHRISTMAS!!!
George runs to the stairs to look for Mary. The wooden ball on the top of the post comes off again, just like every time anyone's used it for over ten years. George is so overjoyed that he has his life back that he kisses it before putting it back.
"Didn't ask any questions, all I had to say was that George was in trouble — 'Count me in!' "
Watch George while Mary is preparing to welcome the townsfolk: he just can't stop kissing her even when she's not paying attention.
Harry: To my big brother George — the richest man in town.
Bear in mind; Harry is a football star, a war hero, and in general he came a lot closer to living George's dreams than George himself ever did. George probably considered himself the loser of the two, and, as this line shows, everyone else disagrees.
"Remember, George: no man is a failure who has friends."
After George reads said inscription:
Mary: What's that?
George: It's a Christmas present from a very dear friend of mine.
A bell on the Christmas tree rings
Zuzu: Look, Daddy. Teacher says, every time a bell rings an angel gets his wings.
Even without the townspeople all chipping in, Sam is more than willing to give George three times what he needs pretty much as soon as he hears there's a problem. Hee-haw.
George and Mary on the telephone together with Sam. George had been in a cranky mood the whole scene, but slowly realizes during the phone conversation that he does truly love Mary. He makes one last-ditch effort to assert his selfish independence, but it's a lost cause.
Sam: Would you tell that guy I'm giving him the chance of a lifetime, do you hear? The chance of a lifetime! Mary: He says it's the chance of a lifetime. George: (clutching Mary) Now you listen to me. I don't want any plastics, and I don't want any ground floors. And I don't want to get married, ever, to anyone. You understand that? I want to do what I want to do. And you're... and you're... Oh, Mary, Mary. (the two kiss passionately)