Are those matte with grey or black iridium polarized? Sku#? If they are polished black, hold them up to direct sunlight and you should see that they are actually red. There are a couple of other indicators. What makes you think they are not authentic? More pics may help.
Yes that screw is supposed to be there; it is holding the band and I believe the arm on. Your fine on my end as far as authenticity, but your best bet would be to go to an O store ir Vault for final clarification.