The best way to handle this is, as soon as the rainbow comes over your Chief's head and he/she sits down, PAUSE THE GAME!!! That way, you can CAREFULLY scour the entire village. And still have time to pick up a child to retrieve it. If I hadn't figured this little jewel out, I would've missed out on my final tortoise shell. It was half-hidden in the waterfall!

I've even found some collectibles barely visible behind the pile of wood, behind the statue, behind trees. You just need to look carefully. Sometimes, all you can see is the little sparkle that is emitted from the collectible.