Another discrepancy is the man to the left of the picture. In the shot w/ dave, you can see someone's elbow on the left, with the rest of the body out of view. In the photograph, the angle would be such that that person would be clearly visible, but he is not there at all.

I think it's just a matter of human error, after a number of takes and having to re-set the shot up to take dave out...then again, LOST is crazy like that...