The Sound of Music/Fridge

Fridge Brilliance

 * Right before Maria seeks advice from the Mother Abess about her love for the Captain, we see the nuns greet a new candidate for their abbey. Some viewers need repeat viewings to realize that the dress the candidate wore is the same one Maria later wore (earlier, Maria said that each woman who enters the abbey has to give away her "worldly clothes") when she visited the Von Trapps again.
 * The family looks confused when Uncle Max announces to the audience that the Von Trapps will be performing an encore, suggesting they weren't expecting to. But he was there when they performed "So Long, Farewell" at the party, and they end up performing again as result of their encore. Thus, that encore announcement may have been a Batman Gambit by Uncle Max to covertly tell them "Try to escape after leaving the stage" by planting the idea in their head through the song. Quite impressive for a guy who otherwise seemed to be The Quisling.
 * How did all those serious looking middle-aged nuns come to Maria's abbey? It's twenty years after World War I. When they took vows there was a shortage of men.

Fridge Logic

 * With What Happened to the Mouse? rolled in. The nuns who sabotaged the Nazis' cars, as well as Uncle Max who they knew was in on the plot... what do you think the Nazis did to them? Doubtful that it was just a slap on the wrist, making for a possible Downer Ending in retrospect.
 * Uncle Max probably had a few tricks up his sleeve. And the nuns didn't tell anyone but Mother Abbess who probably just made them do a few Hail Marys and absolved them.
 * It wouldn't have mattered if the Mother Abbess absolved the nuns. What matters is what the Nazis would have done.
 * Herr Zeller experiences some Fridge Logic during the movie when Uncle Max asks him how many people he knows who communicate with their children while on their honeymoon.
 * In rewatching the scene where the children are introduced, how did the Captain ever figure that the shrill sound of a whistle is any better than shouting?
 * That's how ship captains summoned their men in the old days.
 * And in Real Life, the Captain and his children used the whistles because their estate was large and it was hard to call for each other.