I just finished the game, but there are one area that I didn't visit.
When you left the "accordion" building, there a branch with a disk that block the way, the one with painted flames(?).
The trigger point to rotate this disk is situated just behind and is not accessible. Anybody knows that got past it, and that is situated behind?

What was the point of the branch situated just after (or before, I don't remember exactly) the three discs? It is the dead end with view on the wall with few critters on it.

Also I saw an cowboy ant (surly a famous american person, that I didn't recognized) what says "bully". To what puzzle he is attached? In the same area the father spirit gives a hint about a "good meal" -- I also miss the related puzzle.

Overall I have an impression that I missed around 1/3 of the game.

[MINOR SPOILERS] There's a wallcart you can get access to that is on the other side of that disc, and rotating it is how you get it on the main tracks. Chances are you aren't really missing anything apart from the fact that cart exists. Not sure, but The Neverhood's lake wallcart had a few path branches that were dead ends near some minor points of interests. So it's not exactly unusual. Although, it does show that there are many critters sitting on the wall, which is related to the part where you shoot an egg out of a cannon and into their nest. That "famous american person" happens to be Theodore Roosevelt (hence the expression). They're PresidANTs, you see. ^_^;;; Father specifically tells you to ignore him if you try to get hints from the nearby statue. Well, the only "meals" in the game are the puzzles where you put that fly into a bowl for Beak Beak to swallow it and grow wings...

(I'm still curious about the black wallcart, though...)