Factual error: Scully reads to Mulder from a book all about flukes (Trematodes). However, the information she is quoting is wrong. She states that flukes or flatworms have a "scolex" with hooks and suckers. These are actually the distinguishing characteristic of cestodes (tapeworms). Trematodes have no scolex and definitely no hooks. (00:17:30)
Continuity mistake: Towards The End of the episode there is a scene where Mulder is talking to another agent next to an ambulance and it is shot at night despite it being morning only a couple of seconds ago. (00:33:53)
Character mistake: Surprisingly, it took Scully quite a long time to realize that the tattoo on the victim's forearm is in Cyrillic lettering. (00:24:00)
Answer: As he stated many times throughout the series, Mulder needed Scully to be sober and skeptical. Whenever Scully's skepticism wavered and she started questioning her own rationality, Mulder would try to restore her sense of skepticism, because he needed her to be clear-thinking.
Charles Austin Miller