Factual error: Mulder refers to a Royal Navy vessel that sailed from Leeds. No large ship can sail from there - it is at least 50 miles from the coast.
Die Hand die Verletzt - S2-E14
Factual error: Mulder sees water going down the drain counterclockwise and says something is up since all water in the northern hemisphere drains clockwise. This is not true. Water can drain in both directions in both hemispheres. Things like convection currents, basin design, and residual swirl from filling the sink have a much greater influence. You would have to drain a small ocean to see the Coriolis effect, or use specially-designed test apparatus. See http://www.snopes.com/science/coriolis.htm and http://www.physics.ohio-state.edu/~dvandom/Edu/newcor.html (scroll down to *5.2. Water Going The Wrong Way Down The Sink* near the bottom of the page).
Factual error: The flag in Skinner's office is hung upside-down. (00:28:00)
Factual error: The Arecibo Radio Telescope is abandoned when Mulder goes there. However, after SETI was cancelled, the telescope was still used for other things. (00:16:50)
Factual error: Scully makes a reference to an F.B.I. field office in Kansas City, however, no such office existed at the time of this episode. (00:13:10)
Factual error: Mulder mentions the USS Eldridge as disappearing from Philadelphia (and later reappearing in Norfolk) "nine months after Roswell", i.e., May 1948. In fact, the supposed incident took place much earlier - in February 1943, according to almost all reliable sources. (00:06:50)
Factual error: The townspeople contracted Creutzfeldt-Jakob disease (CJD) from the bodies they consumed and it showed up in the brain tissue within a matter of weeks. However, this extremely rare disease takes several years to even be detectable. (00:18:55)
Factual error: Mulder says that the events occur near I-10, however, I-10 is nearly 200 miles south of Arkansas's border in southern Louisiana.
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)
Factual error: It's quite strange that only after Mulder looks into the ashtray he realizes that the Smoking Man has been in the car. Mulder should smell the scent of cigarettes immediately after entering the car, especially if he is a non-smoker. (00:36:05)
Factual error: In the opening sequence, we see a nuclear attack submarine beneath the ice in the Arctic Ocean. When the captain orders the ship to surface, one of the crewmen mutters, "Surface to what? We're under 32 feet of glacial ice!" Except that they're not under "glacial ice," they're under Arctic sea ice, which ranges from about 6 feet thick in the summer to about 15 feet thick in the winter.
Soft Light - S2-E23
Factual error: Dr Banton's shadow devours the second policeman, however Banton cannot cast a shadow in that direction. (00:11:35)
Die Hand die Verletzt - S2-E14
Factual error: The loss of blood Shannon suffered was definitely insufficient to be the cause of her death. (00:25:00)
Anasazi (1) - S2-E25
Factual error: It is completely impossible the Thinker has made a digital copy that cannot be duplicated.
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