Only USCIS/KCC will know when a picture is rejected but I assume they won't check all the million of entries. IMO they will check the picture when you are chosen by the comp....that to me makes the most sense and doesn't waste time to check millions of pictures, neither IMO they will check all the millions of entries for eligibility, until some one has been chosen, and even then....some one on this forum stated he was rejected later due to not being eligible due to his country of birth, so he received a NL first...