Tunguska (1) - S4-E8
Factual error: This is probably the first time in history of civilized mankind that a person with a diplomatic visa is full-body-cavity searched, not to mention the illegal opening of the diplomatic bag. (00:04:05)
Musings of a Cigarette-Smoking Man - S4-E7
Character mistake: Ramón Mercader did not assassinate Leon Trotsky with an ice pick, as Frohike claims, but with an ice axe. (00:03:00)
Other mistake: When the attackers leave the sheriff's house they walk and run as normal people, although in previous scenes they walk in a clumsy way. The same in the scene with chasing pigs. (00:23:00)
Continuity mistake: In The Beginning, when the Bounty Hunter gets out of his car, Jeremiah Smith says nothing. However, in the same scene at 42:08 in the "Talitha Cumi" episode, Jeremiah says "He is here to kill me." (00:00:05)
Musings of a Cigarette-Smoking Man - S4-E7
Revealing mistake: As the smoking man sits on a bench after finding out his story was rewritten, there are mountains visible in the background. Atop one of the buildings in the background is a Canadian flag waving in the wind. This show was shot in Vancouver, but is set in Washington D.C. There are no tall mountains that close to D.C.
Factual error: The episode is supposed to take place in Traverse City, Michigan, United States. Mountains are visible in the sequence when Mulder is chasing after the killer on foot. The show was shot in Vancouver, British Columbia.
Musings of a Cigarette-Smoking Man - S4-E7
Factual error: In the US classified information system there is "compartmented information", but there's no "compartmentalised information." (00:08:00)
Unrequited - S4-E16
Revealing mistake: The handle and latch next to the supposedly working intercom on the chain-link security gate entrance to the "White Hand" facility is obviously non-functioning - when the gate is opened it can be seen there are no functional operating parts. (00:08:40 - 00:09:15)
Never Again - S4-E13
Factual error: The first time we see Ed's tattoo, it is supposed to have been freshly done and he even removes the new bandage. However, there is no blood or excess ink on his arm, no redness around the lines, no swelling at all; no way at all that it could be a fresh tattoo.
The Field Where I Died - S4-E5
Continuity mistake: When Scully is searching through the pictures to find Sarah Kavanaugh and Sullivan Biddle, she turns the photographs over and they have a label on them to say who they are. Yet when the shot changes angle to show the photos from the back, the labels have disappeared.
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