Just listened, again, to the first two minutes.

It's funny to listen to the hapless Robert Preston trying to retain a shred of dignity while this song barrels down the highway. You can hear a few little imperfections in the singing, suggesting that it was recorded in the fewest possible takes.

But the orchestra (everything but the kitchen sink) and that chorus of youthful voices were all recorded separateley, then the tracks put together, according to the webpage for the...shoot, I forget which webpage said that...