Factual error: The subtitles state an office in Maryland, but in front of the building, we can see California's flag. (00:06:37)
Visible crew/equipment: When Mulder and Scully enter the abandoned mine through a doorway, the viewer can see at right in the distance a number of people sitting on a wall, and one crouching in front of the wall with what looks like a dog. They are sitting still, but there is still movement there. (00:16:00)
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.
Visible crew/equipment: I don't know if this is visible in all formats, but on the newest UK release on DVD, watching in widescreen, it's amazingly obvious. When Mulder recovers from the vampire attack, he gets up from the floor and breaks up a chair to make a stake. There is a shot of his feet as he smashes the legs off and bends to pick up a piece. In the bottom left hand corner of the screen, you can see a crew member's hand carefully and quickly placing a piece of wood on top of the pile for Mulder to pick up.
Clyde Bruckman's Final Repose - S3-E4
Continuity mistake: Clyde Bruckman commits suicide by placing a plastic bag over his head until he asphyxiates. However, when Mulder and Scully first discover him you can see in the shot just before Scully holds his hands that there is no plastic bag around his head (may only be visible in widescreen format). (00:42:55)
Visible crew/equipment: A mic boom operator is visible on the left hand side of the screen wearing a white t-shirt, beige shorts, and sneakers. He's carrying the boom mic and following Mulder and Scully. You can see him when Mulder and Scully arrive at the "Church of God with Signs and Wonders" for the first time...when Mulder delivers the line "That's funny, I knew a couple Catholic schoolgirls who were experts at it." (00:08:20)
Continuity mistake: When Mulder is in the tram car ascending the mountain to rescue Scully, he pulls all of the things out of under the top left-hand seat, but when the scene moves to Krycek in the booth, you don't see any of the things that Mulder threw out. (00:19:40 - 00:20:50)
Redux II (3) - S5-E2
Continuity mistake: Although the subtitle states 12:00 AM, Mulder's watch hands mark 02:35. (00:43:16 - 00:43:39)
Continuity mistake: When Mulder helps Max lie down he notices the scar behind his right ear but when he tells Scully about it later he says that the scar is behind his left ear. (00:29:45 - 00:31:00)
Continuity mistake: Howard Graves' tombstone states that he died on the 5th of October, but the opening scene's date stamp says the 22nd of September, when it was supposed to be two weeks after Graves had died. (00:11:40 - 00:19:55)
Revealing mistake: While the computer is being infected with the virus, Peterson turns away from the screen to face Scully. Two seconds later, after the shot of Scully, the same shot is shown again but in reverse so that Peterson turns back to the screen. It's more obvious if you look at the weird way his eyes blink in the reversed shot. (00:39:50 - 00:41:32)
Visible crew/equipment: As Fox is being led into the jail, when Scully says, "Mulder" the boom mic is at the top of the screen, while she's walking towards him. (00:20:30)
Continuity mistake: In the first footage of the episode we can see that the ambulance's lower right lamp is off. However, at the moment of the crash it is on. Not to mention that the Chevrolet logo, previously seen at the ambulance front, has vanished. We conclude it is not the same vehicle. (00:00:10 - 00:01:06)
Factual error: In the footage's right-hand side, we can see the Church of the Covenant's facade, which is located at East 42nd St. New York. However, the subtitle erroneously states 46th St. (00:09:40)
Anasazi (1) - S2-E25
Continuity mistake: When the military man approaches the Cancer Man we can see at the background the helicopter's left-hand side. When they move towards the helicopter, now closer to them, we see its right-hand side. (00:40:14)
Factual error: A 747 jumbo jet is shown in the first scene of the episode. Later we can see the aircraft cabin with a 3X3 seat configuration. However, there is no 747 with such layout. (00:01:40)
Musings of a Cigarette-Smoking Man - S4-E7
Other mistake: When the CSM is aiming at the door, it must be quite difficult for him because it seems that he forgot to take off the protective lid from the night vision rifle sight. (00:35:10)
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