Small Plastic Piece Fell Out
 

As I was taking off my right tail light housing, a small piece of plastic fell out from somewhere onto the ground. Does anybody have any idea what this piece is for? Can I live without the piece of plastic or would it potentially cause problems?

http://i61.tinypic.com/o5pzjs.jpg

I believe it is a guide for making sure the lamp is correctly installed. I think when I installed my Valenti's I saw them on the stock ones when I removed them. I think someone had posted to be careful when removing the stock ones so you didn't break this off. Not sure it will allow any moisture into the lamp or not.

I believe it's just a plastic tab for alignment during assembly. Mine broke, but the light is still very firmly mounted to the body, I can't get it to move or wiggle at all. If there's a small hole left behind, you could use a sealant putty to seal it up.

OH NO ANOTHER PLACE FOR THESE TAILLIGHTS TO LEAK?????
lol

Like others said it's factory leftover crap; I found one in my trunk, I saved it JIC but eh haven't needed it in 2+ years.