Doc Robbins holds up the vial containing the fatal bullet top-and-bottom between his thumb and index finger. In the close-up of the vial, Doc is holding it by the cap.
Nick Stokes finds a loose diamond mixed in with the smashed glass he is examining. When he puts it under a microscope, he sees a laser inscribed serial number. But the number is shown to be on one of the diamonds facets. Serial numbers are not inscribed on a gems facets, they are inscribed on a gems girdle (a flat area between the top and bottom of the gem).