The animation director Richard Williams is legend. He does stuff in this movie that NOBODY else would do. "Somethin's Cookin" is one of the most insane pieces of hand-drawn animation I've seen.
View: https://www.youtube.com/watch?v=5mKE0UCl5Cg
The minutia here is complete insanity.
0:23 - Animating the perspective on the floor slats, the crib, and the chair. Nowadays this is just a typical CG shot. Back then, you were like "what the fuck am looking at."
0:55 - More perspective animation wizardry. The fucking TILES! Someone had to paint that by hand!
1:25 - What the fuck
2:31 - This isn't CG, and they messed up the shot because they spelled 'Chili" with two Ls (animated in the UK) so they had to redo the whole thing
3:16 - How do you even move the camera like that
And almost all of this is done on ones. What. The. Fuck.
If you look up Williams' THE THIEF AND THE COBBLER, it contains shots that make these look utterly simple in comparison.