Danny Kaye singing Inchworm in the movie Hans Christian Andersen

The "triplets" and "shoe shine" scenes in Bandwagon

Every song in Mary Poppins

The scene in Casablanca when they drown out the Germans by singing the La Marseillaise.

The musical duel between the baroque trumpet and the male soprano in Farinelli (an extremely underrated gem of a movie)

The scene in Back to the Future when he introduces Rock & Roll to the 1955 prom

The threatening music that signals the looming approach of the shark in Jaws (without which that shark isn't scary at all).

The scene in Schindler's List where the children are being led to their deaths as if they were being taken on a school picnic, while we hear a children's chorus in the soundtrack singing the Yiddish lullabye Oifn Pripetshik