Thanks for playing, we'll keep the amount of dialogue we have more in mind next time :D
Regarding collecting missing items at a later point, that should be possible from the main menu. Clicking 'Continue' should take you to a level select screen from which you can choose to replay any level you wish. Now that you mention it though, we never say that this ability exists in the game. We'll have to have a think to see if we can come up with a way to make it clearer :)
Thanks again for playing!