The nuns, when they calmly reveal they sabotaged the Nazis' cars:
"Reverend Mother? I have sinned." (the Sisters reveal parts that they pulled from the cars' engines)
Maria riling Georg up enough to call her Captain.
"How clumsy of me. I meant to accuse you."
Georg confronting Rolf, buying time for his family to escape. And then walking forward and taking the gun out of his hand.
The dinner scene. Despite all the nasty tricks they've played on her - including putting a pine cone on her chair - Maria kindly and near effortlessly shames the children into tears at how badly they've treated her. Captain von Trapp, surrounded by bawling kids and rather taken back, has this to say:
Captain von Trapp: Fraulein, is it to be at every meal, or merely at dinnertime, that you intend on leading us all through this rare and wonderful new world of... indigestion?
Maria (after sipping her soup and looking around calmly at the sobbing children):...Oh they're all right, captain; they're just happy.
On stage at the festival, Max openly gives the details of the Nazis' upcoming attempt to pressgang the Captain into the navy. They go right for him when the family disappears and you know it probably doesn't end well for him, but that's some bravery.
Audra McDonald's performance of "Climb Every Mountain" in the 2013 live show. Every time the camera cuts to Carrie Underwood, it's clear we're not seeing Maria, but Carrie herself realizing what a privilege it is to get a front row seat to this phenomenal singer.
Upon coming home from his honeymoon after the Nazis have invaded Austria, Captain von Trapp takes the Nazi flag he's meant to hang over his home and tears it in half without a moment's hesitation. Possibly the most understated moment of awesome in the whole movie.