Continuity mistake: During the Re-qualification practice shoot scene Dupre as agent Willis fires until he suffers a failure-to-eject stoppage (stovepipe), despite staring at the ejection port throughout the preceding drill he fails to recognise and clear this (as any firearm user would, especially a bank robber with the partial memories of an FBI agent/instructor), and could potentially still have rounds in the magazine. At the next camera change the slide is fully back despite no manipulation from Dupre, as he removes an empty magazine. (00:19:01)
Unrequited - S4-E16
Factual error: By its uniforms, rank insignia (i.e. point-down chevrons), drill and instrumentation (e.g. tubas instead of sousaphones), the military band performing at the re-dedication ceremony at the Vietnam War memorial in Washington is a Commonwealth (probably Canadian) band and not an American band. Unlikely at a formal military ceremony in the United States.
Other mistake: This episode establishes that whenever Pinker Rawls passes through solid matter, his clothes remain behind, as anything he is wearing does not share his ability. However, late in the episode when Jackie throws the pot of boiling hot soup at him, the soup is shown to completely pass through his shirt, when it should have stuck to his shirt instead.
Continuity mistake: While Mulder is picking himself up in the synagogue's attic after being pushed/tripped, you can see that his gun is unloaded, with no magazine. (00:25:07)
Character mistake: Scully gives a description that Eve is driving a Blue Carolla. However in the next scene, Eve is driving a Pontiac, not a Toyota. (00:28:00 - 00:28:51)
Factual error: The local Pasadena station code is WXDL, however it should start with a K not a W. (00:00:05)
Revealing mistake: At The Beginning of the episode we see Duane being abducted and he begins to scream. Look at the "alien" on the left of the screen near to the top of the bed and you will see him move his head revealing where the suit ends and neck/head begins. (00:02:12)
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)
Continuity mistake: At The End of the episode, when Lyle is transforming in the bathroom, we see his hand perfectly shred a shower curtain, however in the next shot we see his hands and they are still fully human. There's no way he could have done that. (00:38:44)
Continuity mistake: During the very beginning of the episode when the cop and researcher are talking on the shore they go from facing each other to the cop facing the lake and having to turn his head to talk to the researcher between shots. (00:00:30)
Continuity mistake: Scully pushes Pfaster into the bathtub and he gets out soaking wet however when he leaves the bathroom and begins to chase Scully around the house his clothes are bone dry. (00:41:20)
Revealing mistake: When Mulder, Scully and the other agent are looking at the covered body of the dead prostitute if you look closely you can see her chest rising and falling. (00:17:22)
Revealing mistake: During the opening funeral scene if you look closely you can see the dead girl breathe. (00:02:28)
Born Again - S1-E22
Continuity mistake: When Felder is being strangled to death by his scarf getting trapped in the bus door, pay attention to the bus driver throughout the sequence. He is a young black guy for most of the sequence however there is one shot from the front of the bus were you can see he has suddenly changed to a white man. (00:21:53)
Visible crew/equipment: When female Marty gets out of the car for the police officer if you look at the left side of the screen you can see the male Marty actor stood there wearing matching clothing and watching the filming. (00:36:33)
Other mistake: At The Beginning when Mulder and Scully leave the room and walk across the FBI office you can see and hear the camera get knocked to the left by something (it was probably the filing cabinet that they walk past a second later). (00:05:19)
Revealing mistake: At The Beginning of the episode Darlene burns her hand trying to open the door, she then puts on an oven mitt and opens the door. If you look closely though she still uses her other naked hand as well as the covered hand to open the door and her naked hand is completely unhurt.
Revealing mistake: After Scully handcuffs Tooms to the bathtub there is a close up of his face and you can see the edge of his contact lens. (00:39:07)
Audio problem: Scully asks the deputy if the vests are necessary and he replies in the same scene. His mouth is way off from his reply. It's likely this is because the show was shown on 4:3 aspect ratio televisions at the time, and he would simply not be visible. Because the show was shot in 16:9, he is very much visible on modern televisions and the mistake is incredibly obvious.
Factual error: The package Scully receives lists her city, state, and zip code as Bethesda, Maryland 20880. While that is an actual zip code in Maryland, it is for Washington Grove, not Bethesda.
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