Continuity mistake: When they find the felled ancient tree, the stump that Mulder clambers up onto to investigate the growth rings has a distinctive crack at the center and the growth rings are irregular in shape. However the stump that we get a close up of has no crack and regular circular rings. (00:18:20)
Continuity mistake: When they find the cocoon, the body inside is completely different in appearance from one shot to the next shot of it.
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