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)
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)
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: 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 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)
Colony (1) - S2-E16
Continuity mistake: When the doctor leaves the common room, he is holding a chart in his left hand, but when he is running down the corridor, both his hands are free. (00:04:40)
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)
Continuity mistake: When Dr Cabrera says "Let him go," the blonde female assistant is on the left of the male assistant, but in the next shot she is on his right. (00:39:30)
Continuity mistake: When doctors make a cut on Cassandra's belly, the green substance comes out of the cut and pours down directly onto the piece of blue cloth she is covered with. In the next shot the fragment of cloth that was in contact with the substance is dry, but in the following shot, there is a large soaked stain on the piece of cloth. (00:00:50)
Continuity mistake: When the CSM discovers the bright spot on the carpet, he immediately realises that Mulder's apartment was under surveillance. However, one can notice that soon after entering Mulder's apartment, the CSM looks down at the floor and carpet covered with blood and there is no bright spot. (00:14:00)
Continuity mistake: The truck stolen by Mulder from the Russian labor camp is Unimog 406. However, during the accident scene, when it comes out of the woods and falls from the hill, it miraculously turns into Unimog 404 model. (00:13:30)
Continuity mistake: During the meeting at a horse track, after the CSM says "You need my expertise, " the First Elder raises his head. In the following shot from the other side, he raises it again. (00:21:00)
Continuity mistake: When Mulder and Scully talk about the piece of skin while driving to the reservation, one can see that there are green trees from the Mulder's side of the road, but when the shot is taken from the outside of the car, there are only grey bushes and landscape devoid of nearby trees on both sides of the road. (00:07:00)
Continuity mistake: When we see Dana Scully after being abducted she has an instrument in the middle of her stomach, inflating it. When we see it in the first shot there is nothing but the instrument, then in the next shot there are gauze pads taped down all around it.
Continuity mistake: When Mulder tells Krycek to go to the bathroom and clean off, in the front shot Krycek holds his right hand raised, while in the back shot his right hand is lowered. (00:42:10)
Invocation - S8-E5
Continuity mistake: When Scully finishes her conversation with Doggett and walks away, there is only one dark-haired policeman watching the crime scene, but when Doggett looks at the crime scene and Mr. Underwood gets up, there is a blond-haired policeman talking with someone. (00:41:55)
Via Negativa - S8-E7
Continuity mistake: When Doggett and Skinner visit Dr. Andre Bormanis at his place, in the first shot from the back he is leaning over some laboratory gear that is holding in his hands, while in the next front shot he is standing upright manipulating on the table with his hands. (00:18:10)
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