Nothing Important Happened Today (1) - S9-E1
Continuity mistake: During the previous episode, Skinner receives a nasty gash on his head courtesy of Billy Miles. This episode takes place 48 hours later and there is no indication whatsoever that Skinner received such an injury (the wound is visible once again in the next episode). (00:15:35)
The Red and the Black (2) - S5-E14
Continuity mistake: While in the car with Scully, Mulder turns his head aside of Scully towards the side window twice: once when the shot is facing Scully, and just after in the shot facing him. (00:40:25)
The Red and the Black (2) - S5-E14
Revealing mistake: It seems that in the first shot the doctor injects something into the vaccine vial rather than extracting from it since the syringe plunger is moving inwards instead of outwards. In the next shot one can see that the syringe is being filled with the vaccine, however the arrangement of doctor's fingers is suitable for injection, which strongly suggests that the scene is played backwards. (00:17:55)
Continuity mistake: Uroff-Koltoff Star of Russia in New York Harbor is a completely different ship from Uroff-Koltoff Star of Russia leaving Vladivostok at 17:45. (00:33:10)
Invocation - S8-E5
Continuity mistake: In this episode the character of Billy Underwood was played by twin brothers Kyle and Ryan Pepi. If you pay attention you can tell when one twin was being used instead of the other as one of them has two freckles on his neck and another two by his right eye whereas the other does not.
Roadrunners - S8-E4
Factual error: At the episode's end, it shows Scully recuperating at the BYU Medical Center in Provo, Utah. However, on the flagpole outside of the center, you can see the Kansas state flag. (00:42:20)
Schizogeny - S5-E9
Revealing mistake: A heavy rain is falling but there is no sign of it on Mulder and Scully. (00:32:00)
Continuity mistake: When the Lone Gunmen speak with Susanne Modeski, in the background there are some cars parked in front of the Stadium Inn. However, just seconds after, when the telephone rings, there is a white truck parked at the entrance. Later on, the cars are back again. (00:38:55)
Continuity mistake: During and just after the Mulder's seizure, when Scully's face is shown, it is at the level of a standing person which suggests that both agents are standing, but in the next shot Mulder and Scully are crouching. (00:31:35)
Other mistake: When examining the bag via X-ray at the airport, Mulder communicates to Scully that he sees three circular pieces inside, however only one circular piece is visible inside the superstructure. (00:31:20)
Other mistake: The landing plane is shown in a incorrect scale - it's too small compared to the sedans chasing Mulder and Scully. (00:32:30)
Factual error: Gonzales shot himself in the forehead but he's got the back of his head intact - no exit wound. (00:27:40)
Other mistake: Sergeant Louis Frish had not enough time to walk down from the air traffic control tower to meet the agents since he was on the top of it when Mulder and Scully drive up to the tower - two persons can be seen on the top of the tower. (00:21:45)
Factual error: In the background the full moon is visible and it's early morning (approx. 6:00 AM). However, at the start of the episode we see the full moon at night (approx. 19:50). Due to the fact that these are consecutive days, this situation is impossible from an astronomic point of view. (00:14:35)
Factual error: The last number on the truck's license plate is "77." On Russian plates the last two/three digits stand for a registration place. "77" is a number for Moscow, but the Gulag is located in Krasnoyarsk region, so the number should be different. Besides, the format of the plate (LDDDDL|DD) is incorrect - the correct one is LDDDLL|DD (L - letter, D - digit). (00:11:05)
Character mistake: Vassily Peskov speaks Russian with a strong accent. This is because the actor who plays Peskov (Jan Rubes) was from former Czechoslovakia.
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)
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