Deep Throat - S1-E2
Other mistake: When Scully and Mulder are pulled over by the government agents, one agent takes and unloads Scully's gun. When he removes the magazine you can see it has only one bullet in it, as this model of magazine has cutaway sides to show the amount of bullets in them. (00:26:47)
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