Elinor changing back into her human self at the end of the film. Especially the royal family group hug afterwards. And the clans looking on surprised and happy to see the queen again.
Elinor realizing that forcing Merida into marriage is wrong, and allowing her to back out and get married if and when she chooses.
And Merida's own actions in that scene — she's totally willing to make a sacrifice and do what has to be done to save her mother and prevent another war, but as soon as that's not 100% necessary she finds a peaceful and suitable solution that not only gives her what she wants but gives her suitors what they've really wanted also. They're every bit as reluctant as she is, so her getting rid of official marriages of alliance isn't surly teenage rebellion — it's her first act as a prudent future ruler to break from tradition so the kingdom can grow and progress.
The lords finally coming around to the decision to respect their sons' wishes, with all three respectfully bowing to Merida.
Elinor and Fergus's marriage is a Crowning Relationship of Heartwarming. Despite the fact that it was an arranged marriage, it's a very, veryhappy one.
Every time Merida is in danger, Bear!Elinor always reaches out to protect her; i.e., when she saw her own shadow and thought there was a bear in the room, she immediately flung an arm out to protect Merida. When the witch's cottage collapses, she embraces Merida to protect her from the debris. And then there's the literal exhibition of the Mama Bear trope when Bear!Elinor goes completely berserk on Mor'du after it threatened Merida.
There's a new tapestry. One that shows Bear!Elinor and Merida holding hands.
Right after the film ends, the black screen comes up. On it is one last animation of a Wisp, and under it is "In memory of Steve Jobs". That might be slightly meta, but it sure is heartwarming.
The spirit of the prince who became Mordu, rising from the now crushed body of the bear, nods in thanks to Elinor for freeing him from his curse.
During the departure scene of the three clans, we see the big scary scar covered warrior of the Dingwall clan clearly being romantic with the small plump maid.
During the final battle, there's an almost Freeze Frame Bonus of young Macintosh worriedly helping his father up off the ground. Considering the fact that his character is originally portrayed as arrogant and full of himself, it's a peek at the real person under all that competitiveness.
Brenda Chapman's inspiration for the story is her relationship with her daughter.
At the beginning, Merida's free day. You know you just feel like a kid again after watching it.