Visible crew/equipment: As Scully rolls down the stairs with the killer at The End of the episode, once they reach the bottom a hand pops out from the left side of the screen.
Visible crew/equipment: After talking to the scientist about his car, Mulder and Scully are talking in front of a door. In the glass of the door is a reflection of a third person.
Visible crew/equipment: During the scene when Mulder, Scully and the deputy approach the farmhouse there is a moment when Scully walks up to a chicken coop and a boom microphone with a fluffy wind cover on can be seen coming up from the bottom of the screen (Underneath Scully). (00:30:35)
Deep Throat - S1-E2
Visible crew/equipment: When Mulder and Scully attempt to interview Col. Kissell, as he gets out of his car, you can see a square light reflector screen reflected on the car door. (00:12:37)
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)
Visible crew/equipment: After Lieutenant Colonel Stans (who has severe burns all over his body) kills Leonard Trimble, he turns to the camera, where his bathrobe is not fully covering the burn mask he is wearing, exposing a part of his shoulder and the edge of the mask. (00:42:35)
Visible crew/equipment: At The Beginning of the police car chase, the officer escorting Scully gets into a cruiser. The camera is reflected in the driver side window when he opens the door.
Visible crew/equipment: At the silo in North Dakota, the camera pans around the vehicle after Mulder and Scully arrive. The boom mic is reflected in the passenger doors.
Within (1) - S8-E1
Visible crew/equipment: When Scully is looking at her reflection in the mirror, the camera moves toward her and its shadow appears on the left side of the mirror's frame. (00:02:00)
Visible crew/equipment: In the final scene of the episode, when the camera goes up, its shadow can be seen on the left side of the screen. (00:42:15)
Visible crew/equipment: When Ben Drake is walking in front of the paintings in his office, for a short moment one can see the camera setup and the cameraman reflected off the first painting. (00:01:40)
Visible crew/equipment: When the apartment owner comes over to the killer's apartment, she puts an envelope over near others. Right as she notices the flies, the camera tracks to the left and back. You can see its shadow cast on the wall to the left.
Visible crew/equipment: When Mulder and Scully are talking to the owner of the trailer park and he is berating Mulder, you can see the edge of the lens in the upper left corner of one shot. This is because the lens used was of a wide angle almost fish-eye type and the edge of the lens itself can occasionally creep into the frame on most cameras.
Visible crew/equipment: Near The Beginning, Mulder, Scully, and another man are walking through a graveyard. The camera is following them to the right passing head stones. The crew can be seen reflected in a black shiny head stone as the camera passes.
Visible crew/equipment: When the Senator opens his car doors, a filming crew member in blue jeans is reflected in the door. (00:32:25)
Visible crew/equipment: Mulder talks to the man from NICAP on the other side of the fence. When the shot is looking at the man, film lights are visible reflected in his glasses. Since he is looking at Mulder, there should be lights on Mulder's side, but there are none.
Visible crew/equipment: Mulder is talking to the computer programmer in the prison. The shot starts on the bars and pulls back. A significant shadow caused by the camera is visible on the right side of the frame.
Mind's Eye - S5-E16
Visible crew/equipment: During the scene of Marty's interrogation there is some dark blue element behind Mulder when he is reflected in the mirror. However, in the frontal scene there is just a plain wall behind him. (00:24:00)
Visible crew/equipment: When Mulder is driving away from the gas station, crew members as well as some filming equipment can be seen reflected in the car's body. Mulder is in a pretty desolate area, so seeing people reflected in the car's body would in all likelihood be crew members and not random citizens. (00:28:30)
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