When Mulder and Scully arrive at Mrs. Thibedeaux's home in Edmond, Nebraska, after she is attacked by B.J., Mulder phones for an ambulance and then immediately leaves, going directly from there to Cokely's house in Gainesville, Nebraska. Meanwhile Scully - presumably after waiting for the EMT's to show up - takes Mrs. Thibedeaux back to the police station in Aubrey, Missouri, to be interviewed by Det. Tillman. After the interview Scully and Tillman then also go to Cokely's house back in Nebraska, somehow managing to arrive mere minutes after Mulder gets there.
Towards the end, when Mulder arrives at Mrs Thibedeaux's place, when he opens the door, you can see the sound-man, his perch and the mic in the reflection of the door.
Just after the teaser, Mulder and Scully are looking at the dental radiographs. Scully points out that the man is "congenitally" missing a lower left bicuspid. It is impossible to tell if the reason why the tooth is no longer present is congenital from the radiograph. Congenital is a condition existing at birth.
At around 25:32, Scully is seen tripping and losing her balance for a moment while running down the stairs in the background.