Oh no, you got bit by the carpet monster!! At every builders work area is a wormhole that you must sacrifice at least one part to on every build, one that no matter how much you clean and investigate it's just....gone. One day after we go on the the great beyond, we'll find all these missing parts. Like the one missing sock, it may just run away or be taken by gremlins.
Seriously though, well, I was being serious, sometimes they fall off the tree and my be in the plastic bag, or fall on the floor and bounce to an area you'd never think of. Those little suckers can have a mighty bounce, better than a football (not socker ball).
Once all has been exhausted, one may try to get another piece from the manufacturer. I'm not familiar with Trumpeter's customer service, but they should have a US contact center where you can email and see if you can get a new part. Some companes are fantastic about sending out a part, or the entire tree, right away free of charge (the old Revell) others aren't even responsive to your plite.
Do you have Testers extra thin cement? It works wonders and a small drop at the bow seam along with a clothespin will close that bow gap toot sweet. You can get it at Hobby Lobby with their 40% off coupon, along with other little goodies.