You hit the precision levels quite niceley, and I think the use of pitch bend is really inspired (for balloons zipping around or as a reference to stretching rubber) - I particularly like how you use that as a transition medium between instruments, going from the lower accordion to a high violin sound and back.
The pitch bends do in part feel quite strange, because you are bending instruments that can't naturally do that (like the accordion). As so often, this is an opinion based on taste and should not be taken as fact, but I think it might have helped to make your piece "believable" had it been made with obviously synthetic sounds, like chiptunes or classic synth patches.
Also, your tempo change at the 2:00 mark is quite abrupt and dispells any illusion that there are actual musicians playing this section - a more gradual change would make it more natural again. 
And then we come to the end, which again, is just inspired - a hectic crescendo and then everything is just dropping off a cliff, like a deflating balloon. Very nice!