Continuity mistake: In the close-up shot of Mulder just before he shoots Barnett, his black ear piece disappears. (00:42:15)
Continuity mistake: In the scene at the start, when the police car passes the truck, clearly it is daylight, but right after the truck shuts down it is completely dark. (00:03:25)
Continuity mistake: When Scully changes the refill of her ball-pen, in the right shot she keeps it under the desk while in the next left shot she holds it over the desk. (00:12:20)
Continuity mistake: When Mulder walks around Scully, he passes her by, however in the next shot he is again behind her. (00:16:10)
Miracle Man - S1-E18
Continuity mistake: The young Samuel stretches his palms upwards, while in the next shot the boy holds them straight. (00:01:00)
Miracle Man - S1-E18
Continuity mistake: In the establishing shot of the courthouse the subtitle reads "Kenwood County Courthouse" but you can read on the building that it is the "DeKalb County Courthouse". (00:15:15)
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: 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: When they find the felled ancient tree, the stump that Mulder clambers up onto to investigate the growth rings has a distinctive crack at the center and the growth rings are irregular in shape. However the stump that we get a close up of has no crack and regular circular rings. (00:18:20)
Continuity mistake: When they find the cocoon, the body inside is completely different in appearance from one shot to the next shot of it.
Continuity mistake: When Tooms walks out of the courtroom, the doctor and the old lady who were sitting in The Beginning of the corridor are missing. (00:11:45)
Born Again - S1-E22
Continuity mistake: When Scully is doing the exam on the dead guy on table, he blinks and breathes. (00:12:05)
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 the Smoking Man brings the alien fetus to the Pentagon storage facility, he places it on the second rack, then in the next shot he walks away from the rack situated in the middle of the corridor. (00:42:55)
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