Deliberate mistake: O'Niel needs a sample of a dead man's blood to test for toxic drugs. So he visits the corpse, which has been dead for quite some time and is lying on its back, and proceeds to insert a hypodermic syringe into the dead man's frontal neck, extracting the sample. But blood pools low in the body soon after death. There ought to have been no blood available from that location of the body. To get blood, O'Niel should've punctured the corpse's underside.