Continuity mistake: When Ray is eating the sandwich, there is a large bite out of one corner just before he removes the foil. In the shot from behind after the foil is removed, the bite is only from one slice of the bread.
Continuity mistake: Just before he removes it, the foil disappears from Ray's sandwich in one shot, then appears again in the next shot.
Continuity mistake: When Scully enters her apartment, the blinds are up and there is quite a lot of light in the room. However, when the flashback with Mulder ends, during which Scully was supposedly standing still, the shades are rolled down and there is much less light in the room. (00:20:30)
Three Words - S8-E16
Continuity mistake: When Mulder sits at the computer terminal in the census records room, we see two empty boxes on the screen, one for an ID and one for a password. The shot cuts to Mulder, then back to the screen and shows him typing the password, while the ID has already been typed in; it is very long and there wasn't time in between shots or nearly enough clicks of keys for Mulder to have entered that ID.
Empedocles - S8-E17
Continuity mistake: When the fiery figure comes up to Jeb, he is standing alone on the street, however in the previous and following take he stands in the crowd surrounded by other people. (00:02:15)
Continuity mistake: When Knowle Rohrer is talking with Agent Doggett face to face in a separate room about the super-soldier project, he is wearing a red FBI badge, but in the previous scene when he came to visit Doggett, he was wearing a regular FBI badge. (00:08:40)
Continuity mistake: When Agent Reyes and Agent Scully are talking about mood music, in some shots Reyes rests her hand on the bed's backrest, while in other shots she firmly grabs it. (00:14:45)
Continuity mistake: When Agent Reyes is aiming at the oncoming car of a ranger, in the front shot the windscreen of the car is completely covered with dirt and fully opaque, while filmed from the ranger's side the windscreen seems to be transparent and relatively clean. (00:17:00)
Continuity mistake: Just before Skinner shoots Alex Krycek in the head, Alex is lying weakly on the ground, having already been shot twice. However, as Skinner makes the kill shot, Alex is suddenly standing and falls to the ground upon impact of the bullet, with no time (or strength) for him to have risen. Also, the last shot of the dead Alex shows his face and his nostrils flare from breathing.
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)
Nothing Important Happened Today (1) - S9-E1
Continuity mistake: When Agent Reyes and Assistant Director Brad Follmer meet in the bar, Brad is holding his glass either by the cup or the stem, depending on the shot. (00:18:20)
Nothing Important Happened Today II (2) - S9-E2
Continuity mistake: After entering the room with the water tank Agent Doggett has dived into, the Assistant Director Brad Follmer screams "Doggett!", while in the same scene in the "Nothing Important Happened Today I" episode he screams "Agent Doggett!" (00:03:35)
Continuity mistake: When Agent Doggett follows Lukesh into the parallel universe trying to find him, Lukesh suddenly reappears from Doggett's left and is pointing at him with the gun held in the left hand, while in the next shot he is aiming at the agent from his right holding the gun in his right hand. (00:03:25)
Continuity mistake: When Natalie stops kissing Dylan, her lips are covered with blood, but the moment she leaves Dylan's room she has no sign of blood on her lips. (00:32:00)
Trust No 1 - S9-E6
Continuity mistake: When Scully reads the alleged printout of the email sent to her by Mulder, it says: "Dearest Dana: I've resisted contacting you for reasons I know you appreciate...I want to come home, to you, to William", but when Scully has previously viewed this message in the internet café, it had a different form: "I've resisted contacting you for reasons I know you continue to appreciate...I want to come home. To you, and to William." (00:06:05)
Trust No 1 - S9-E6
Continuity mistake: When the guy from the NSA is speaking with his supervisor, after the supervisor asks him about his wife and child, in the background he turns his head toward the supervisor, while in the next close-up take he turns his head toward the supervisor again. (00:12:30)
Trust No 1 - S9-E6
Continuity mistake: When Scully is pulling out, in close-ups she holds her cellphone in her left hand, while in distant shots she keeps her left hand on the steering wheel. (00:23:00)
Continuity mistake: Agent Doggett holds the rubbings in his hands and after a while, he hands them over to Agent Reyes. However, when filmed from behind Doggett, the rubbings are in the same position in both situations. (00:07:45)
Continuity mistake: When Agent Scully is leaving her apartment to meet Agent Doggett and Agent Reyes, her mother is holding William in her hands. Depending on the shot, William's head is turned right or left. (00:21:30)
Continuity mistake: Marita Covarrubias tells the tribunal that she used to be Special Representative to the Secretary General of the United Nations. However, in "Herrenvolk," she told Mulder that she was the assistant to the S.R.S.G. (00:39:15)
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