1. The band accompanying the marriage procession with the insane bridegroom in the palanquin plays 'for he is a jolly good fellow' !
2. Aparna's change of heart when she stares out in the courtyard watching a toddler through a rent in the curtain.
3. For his son he is a friend first and father later....poignant !
4. The transitions between scenes, which Ray was so ingenious at:
- a movie screen turns into a carriage's rear window
- a woman's sorrowful sigh is immediately followed by crashing waves
- dissolves of Apu's resting face establish his increasing weariness after his wife's death
Just some examples, of course. Ray's transitions throughout all three "Apu" movies are amazing, on par with Ozu and Ophüls for their pure, elegant poetry.
There is no doubt about the brilliance of these films. And the little things certainly make them.
For me it is the continuing theme of the train that links together the travels, and separates the characters at pivotal times. When the grandfather is left holding the locomotive at the end, the toy the child rejected... that says a lot to me. After so much grief, this future will now be a better one.