Revealing mistake: When Mulder, Scully and the other agent are looking at the covered body of the dead prostitute if you look closely you can see her chest rising and falling. (00:17:22)
Revealing mistake: During the opening funeral scene if you look closely you can see the dead girl breathe. (00:02:28)
Answer: He was being facetious. He doesn't specifically know that information, he was merely giving examples of the types of information he has access to.
I think so too.
lionhead