The very first thing I found was that the navy blue tag looked a little off.
Below are pictures of a real Polo and the fake (I attached 2 because the camera focused on one, then the other and I was too lazy to go back and take individual pictures):
Read more: http://computersight.com/programming/how-to-spot-fake-ralph-lauren-polo-shirts/#ixzz2aJTYRbqc