Factual error: Mulder says that the events occur near I-10, however, I-10 is nearly 200 miles south of Arkansas's border in southern Louisiana.
Continuity mistake: When Martin takes out the nanny-cam from the bear, the lens-protection is on so the camera could not have recorded anything. (00:30:00)
Continuity mistake: When Mulder and Scully first see the artifact rubbing in Skinner's office, the rubbing is quite faint and lightly done. A couple of times during the episode, the rubbing becomes darker and heavier drawn.
Continuity mistake: When Scully arrives to investigate the kid who was crushed by the bleachers the time stamp says 5:10AM. It seems strange that the investigation would start the next morning, unless the high school holds basketball practice at 3:00 in the morning. (00:16:35)
The Sixth Extinction (2) - S7-E1
Revealing mistake: When Scully enters the F.B.I. Building after returning from Africa, she isn't wearing her badge. She'd need it to walk around without being stopped by security. (00:35:50)
Continuity mistake: If the Kernoffs were really devoted Catholics why would they have waited six years to have Dara baptised? (00:00:40)
Factual error: Mulder calls the dust in Maleeni's van "lycopodium powder" that the Los Angeles Police Department used to collect fingerprints, but the real LAPD uses latent print powder not lycopodium. (00:06:35)
Continuity mistake: We see Scully wearing pants while sitting on the couch, but when the real Mulder comes in, she jumps up and we see she's wearing a skirt. (00:38:35 - 00:41:25)
Invocation - S8-E5
Continuity mistake: When the psychic collapses, sun is streaming through the window, indicating early afternoon. When we see the ambulance driving away a few scenes later, it's dark outside. It's highly unlikely it took a medic team several hours to get there and stabilise her.
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: Mulder recalls to Scully that he saw Krycek being pulled out of the car and then saw the bright flash, but he only came to just in time to see the flash. (00:08:50 - 00:12:00)
Continuity mistake: Randall has strange pale eyes but just before he shoots Dwight, when he is aiming the gun at Tammi, there are several close ups of his face and his eyes are a normal brown.
Continuity mistake: In the pre-credits sequence when the gunman is shot by the police officer, he initially clutches a wound on his right side. When he is shown lying down, the bullet wound is higher up and on his left side.
Continuity mistake: When we see the Russian guy get shot and he falls out of his chair, he knocks the chessboard off the table. But when Jeffrey Spender shows his team the tape, the guy hits the board so that it spins around, instead of falling off completely. (00:02:40 - 00:07:55)
Factual error: At the crime scene where Roland killed one of the professors by dunking his head in liquid nitrogen and dropped him on the floor, someone has drawn an outline of the dead prof's body and all the bits his head broke into when Roland dropped him. This outline-drawing doesn't happen in life because it interferes with the crime scene, it's a popular myth.
Factual error: Scully reads to Mulder from a book all about flukes (Trematodes). However, the information she is quoting is wrong. She states that flukes or flatworms have a "scolex" with hooks and suckers. These are actually the distinguishing characteristic of cestodes (tapeworms). Trematodes have no scolex and definitely no hooks. (00:17:30)
Continuity mistake: At The End, when Scully is trying to wipe sand and water from the moving tide away from a section of spacecraft, she stands up and the camera pans out; she is suddenly 3 feet away from the ship and several more away from the tide line.
Continuity mistake: After the part where the head Kindred woman tells Mulder and Scully "I asked you not to interfere", Mulder leads Scully away. From one camera angle, he is leading her away by the hand. In the same scene, but from a different camera angle, he has his arm around her. When we go back to the first camera angle, he is once again leading her away by the hand. (00:33:10)
Continuity mistake: In the mine with the medical records we see Samantha's file. In the season 1 episode "Conduit" we see the X-File Mulder opened on her. In the previous episode she is listed as Samantha T. Mulder and her birth date is 1/22/64. Here we see her name as Samantha Ann Mulder and her birth date as 11/21/65. (00:20:40)
Continuity mistake: Jeremiah Smith and Mulder are with the kids, and in the background, when CSM is looking through the window, Samantha's clone and the other kid disappear.
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