Anasazi (1) - S2-E25
Other mistake: Immediately after a shot has been heard, Mulder, who is in flat #42, grabs his gun and rushes through the corridor passing by flat #47, which means he is still on the same floor. Within 10 seconds after the shot, the next-door lady is already aware of the crime. Not mentioning that 2 seconds later two policemen arrive at the scene. (00:07:21)
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