There's a bug which may be encountered right at the start of the game. The POP vending machine can be clicked repeatedly to spawn a lot of keys which fill your inventory space. They're invisible until you click them, and getting a key this way disables the description box. It's the same key you get by cutting the string, so the vending machine probably shouldn't be clickable at all.
http://www.newgrounds.com/dump/item/c599f582834b28d677d2579a06e2dbe2
The bushes in front of the restrooms don't do anything upon being clicked and don't have a description either, but as far as I know, they cause no bugs.
Also, the "Credits" button on the ending screen doesn't work (unlike the one on the first screen).
Aside from that, the game was good, I think the colour puzzle was clever, and I like the fact the playground's fence had its own description explaining why can't you simply climb over. The bike bowl part seemed a bit weird though (it didn't look so deep you couldn't climb back without a bike), but nevermind. The medal works fine.