Most disturbing scene ...
I love the movie, a great cast and the best scenery shots ever since "Lawrence of Arabia", some action, some humour, and a plot that spans from the early settlers to the coming of the railroad and the end of the "Wild West".
The only scene I find a little disturbing is when Spencer Tracy delivers the final lines, and they show aerial shots of the urban sprawl of modern cities, motorways, monotonous midwest corn fields up to the horizon ... it is like an anticlimax to the movie with all the beautiful landscapes of the Old West, that are now gone forever, and it made me a little sad.