Continuity mistake: When Mulder and Byers find Scully in Penny's room, there is a black stripe on the ceiling of the corridor, while in the scene when Scully is leaving the room there is no stripe there. (00:36:50)
Never Again - S4-E13
Continuity mistake: In the front shot Scully holds the photo with 2 fingers (thumb and index), while in the back shot she uses three fingers (thumb, index, and middle). (00:24:55)
Continuity mistake: When Mulder is talking to Dana's mom about finding her cross (necklace) in the trunk, Scully's mom says that she gave it to her on her 15th birthday, but in Season 5 in Christmas Carol, Scully has a flashback to receiving it at Christmas. (00:41:40 - 00:43:55)
Mind's Eye - S5-E16
Continuity mistake: While talking through the jail glass, Marty's face is generally directed straight toward Mulder's face when reflected in the glass, but her head is twisted to the right when filmed from Mulder's side. (00:34:40)
Mind's Eye - S5-E16
Continuity mistake: When the policeman passes the phone over to Marty, in the first shot from behind she holds it with two hands, while in the next frontal shot she grabs it with her left hand and then with the right hand. (00:13:20)
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)
The Red and the Black (2) - S5-E14
Continuity mistake: While in the car with Scully, Mulder turns his head aside of Scully towards the side window twice: once when the shot is facing Scully, and just after in the shot facing him. (00:40:25)
Continuity mistake: Uroff-Koltoff Star of Russia in New York Harbor is a completely different ship from Uroff-Koltoff Star of Russia leaving Vladivostok at 17:45. (00:33:10)
Invocation - S8-E5
Continuity mistake: In this episode the character of Billy Underwood was played by twin brothers Kyle and Ryan Pepi. If you pay attention you can tell when one twin was being used instead of the other as one of them has two freckles on his neck and another two by his right eye whereas the other does not.
Continuity mistake: When the Lone Gunmen speak with Susanne Modeski, in the background there are some cars parked in front of the Stadium Inn. However, just seconds after, when the telephone rings, there is a white truck parked at the entrance. Later on, the cars are back again. (00:38:55)
Continuity mistake: During and just after the Mulder's seizure, when Scully's face is shown, it is at the level of a standing person which suggests that both agents are standing, but in the next shot Mulder and Scully are crouching. (00:31:35)
Continuity mistake: In The Beginning, when the Bounty Hunter gets out of his car, Jeremiah Smith says nothing. However, in the same scene at 42:08 in the "Talitha Cumi" episode, Jeremiah says "He is here to kill me." (00:00:05)
Continuity mistake: Malcolm Wiggins stabs Alfred Fellig in the back three times, including once in the middle of his back to the right of his spine. However, when Scully is examining Fellig's back later in the episode, he has at least six stab wounds, and all of them are around his shoulder blades. (00:13:30 - 00:18:00)
Continuity mistake: Just as Mulder and Scully are entering the interrogation room to question Lauren for the second time, Mulder is holding a thin stack of paper, folded in half in his right hand. In one shot, these are folded horizontally. In the immediate next shot, they are now folded vertically. (00:34:20)
Continuity mistake: Agent Frank Burst screams "Stop!", but in the previous shot the police car was already stopped, although deputy Scott Kerber has just pushed the accelerator. (00:03:30)
Continuity mistake: After the crash Mulder rests his head on the passenger dashboard, however in the previous shot filmed from the outside he keeps it on the headrest. (00:08:30)
Continuity mistake: While hugging detective White, in the first shot Mulder's tie covers his shirt's collar, but in the next shots the tie is hidden under the collar. (00:26:10)
War of the Coprophages - S3-E12
Continuity mistake: The bug exterminator squeezes his throat with either left or right hand depending on the shot. (00:02:25)
Revelations - S3-E11
Continuity mistake: When filmed from the inside of the basket, the openings in the basket structure are big enough to put a finger into it, while in the outside shot the structure is compact and dense. (00:21:00)
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