Specifically, I'm referring to the balloons available as prizes in the Carnival Prize Tent, and donating them to the Balloon Hunt stand. Currently, all but three of the balloons there can be donated.

The missing ones are:

It seems especially odd that the pig balloon can't be donated when it's one of the choices to pop. :P

Obviously this isn't a big deal, I just thought maybe they could be added for consistency's sake.

Oooh, really? I didn't realize! :o Thanks for explaining why, that satisfies my curiosity! And I guess this can be ignored then. :P