After Valjean stops Javert from arresting Fantine, he carries her to the hospital himself.
When Valjean finds Cosette in the woods, she is terrified of him. To ease her fear, he takes off his hat, gives her a warm smile (all the while looking remarkably like Hugh Jackman) and addresses her as "mademoiselle." Up until this point Cosette has been treated as little more than dirt by every adult that she knows, so his sincere display of kindness instantly wins the little girl over.
And then (in a nice nod to the novel) he buys her the most magnificent doll in the toy store window—the first Christmas gift ever for a little girl who up until that point was making do with a bit of twisted-up rag for a toy.
And the little moment where he swings her up on his arm. SO CUTE!
Valjean: Where I go, you will be. Cosette: Will you be like a Papa to me? Valjean: Yes, Cosette! This is true! I'll be father and mother to you!
The composition of a new song for the film, "Suddenly", which was added to show the wonder of Valjean and Cosette quickly coming to love each other. It is beautiful.
Suddenly the world seems a different place,
Somehow full of grace, full of light.
How was I to know that so much hope was held inside me?
What is past is gone, now we journey on through the night...
In the film, when Valjean and Cosette are cornered by Javert, but manage to escape with the help of Fauchevelant, the man Valjean rescued from the cart earlier.
How the anger and disappointment on Eponine's face disappear when Marius touches her arm and pleads with her to track Cosette down.
Enjolras's smile in "One Day More" when Marius says, "My place is here, I fight with you!"
No so much heartwarming when the reason Marius says the above line is because he's mourning the fact that the woman he fell in love with (in only a couple hours) is now leaving for England, presumably never to return, which has made him suicidal, more or less.
After Gavroche delivers Marius' letter for Cosette to Valjean, right before Gavroche leaves, Valjean tells him, in reference to the barricades, "You stay away from there now, you understand?" Valjean doesn't even know Gavroche's name at this point, he's just a boy carrying a message, but he still wants him to be safe.
Later on, when Valjean arrives at the barricade looking for Marius, everyone suspects him of being a spy and wants to kill him. Gavroche yells at them that he knows him and not to shoot.
When Enjolras discovers that their barricade is the only one left, he urges anyone who wants to leave to do so. Cue Gavroche starting up a short reprise of "Do You Hear The People Sing" which, as it did before, spread through the people present.
In another nod to the novel, when Enjolras is cornered and about to be shot, Grantaire appears in the doorway. He doesn't even look at the soldiers but goes straight to Enjolras' side, where they share a meaningful look before facing the soldiers together. If you look closely, at the moment before they are shot, you can see them clasp hands.
A serious Pet the Dog moment for Javert in the film version. When he searches the bodies of the revolutionaries for Valjean, he spies the corpse of Gavroche, the very boy who ratted him out, endangering his life among the revolutionaries. He bends over, takes off a medal he wears, and remorsefully puts it on Gavroche, as if symbolic of his growing humanity.
Not just any medal, but the Legion d'Honneur, the highest honour bestowed by the French government. At its creation, it was meant to reward outstanding bravery on the battlefield.
Perhaps there is a bit of Fridge Brilliance in this—Gavroche was truly brave, risking his life to get ammo, continuing to retrieve it during the fighting and facing his death defiantly. He really does deserve that medal.
Also Gavroche lived inside the Elephant of the Bastille, which Napoleon Bonaparte had built and in death is given a medal that was issued by the Emperor himself.
The scene where Valjean rescues Marius is slightly different than the book or musical. Originally, they came across Javert, who agreed to let them go if Valjean agreed to come into jail after he dropped off Marius at the hospital. In the movie, Javert instead refuses to let them go, points a gun at Valjean, and says that if he takes one more step, he'll fire. Valjean looks Javert in the eyes for a good ten seconds, turns around, picks up Marius, and starts walking forward. Javert doesn't fire.
Seeing Marius pick Cosette up and spin her around at their wedding is adorable. Even more so considering how much they had suffered during the rest of the story.