Oscar fixing China Girl's legs, mirroring the scene where he couldn't do anything to help the girl in the wheelchair.
It's a small moment, but the fact that the magical force-field let Oscar through (despite some difficulty) despite his and Glinda's fears it would kill him instead.
Oscar's conversation with the China Girl after his confession to Glinda that he is not a real wizard. At first it seems to set up a Third-Act Misunderstanding since the China Girl is standing at the door, wanting to be tucked into bed. But her words to him as he tucks her in clearly show she did in fact hear at least some of their conversation, since she reveals she knows he isn't "the same kind of wizard" as the old king had been, but she still believes in him all the sameóeven when it seems he really has abandoned them in the balloon later, and all the others, from Knuck to Glinda herself, believe the ruse or at least have a moment of doubt.
Oscar's gifts to everybody at the end, but especially for China Girl - he presents her with himself and the other friends he's made (Finley, Knuck, Glinda, and Master Tinker) as her new family, saying that while it's not exactly what she really wants, China Girl says she loves it. Cue Tears of Joy.