When the agents ask Dwight to identify a document a few inches from his face he tells them that he is legally blind and can't read it. But earlier in the show he tells Tammy that the message light is blinking on the answering machine which is several feet away from him.
This can be explained as the definition of "legally blind" is "...central visual acuity of 20/200 or less in the better eye with the use of a correcting lens...", so while he cannot read even with corrective lenses it is possible that he can perceive light, shadow, and motion sufficiently to recognize the blinking message light.
Scully states that they tracked the call Chase made to Surekill via his calling card. When he was shown making the call, he simply punched in the phone number.
8:46 - as Dwight turns to walk away and lady gives her "Dwight" line, there is a visible boom-mic next to his ear.
In this episode Agent Doggett mentioned the name Clark Kent. This is the alias for Superman a DC Comics superhero who is an alien from a planet called Krypton. He came to earth in a spaceship.
Normal bullets don't usually travel through so much material as to be able to kill someone from through a room, much less several rooms. In the first murder, why would the bullet go through several floors of metal/concrete, etc. and just stop in the victims head?
Comment: They mention that the first murder involved armour piercing rounds.
Comment on comment: At best, a 9mm armour piercing round can only penetrate about 3mm of steel plate and would not have the power to penetrate the types of materials shown in the episode.
Doggett: Dwight Cooper. Arrested in 1986.
Scully: For Grand Theft Auto.
Doggett: Right. How does a legally blind guy steal a car?
Scully: Well, I assume that he had a partner doing the driving.
Doggett: The brother he mentioned — Randall Cooper. They were arrested together. Although Randall apparently didn't serve much time.
Scully: They share the same birthday. They're twins.
Doggett: I hate twins. Twins never rat each other out.
Scully: Well, maybe there's someone in that office who will.
Doggett: So, lucky Shot?
Scully: Very. This victim here stated that he was going to be killed, just moments before he was shot which doesn't sound lucky at all.
Doggett: Guess I can't argue with that
Gregory Nathan Boniface 1970-2000
In the end credits the actor who played gangbanger#2 is mention "In Memoriam". This X-Files episode was his last work and was aired after his death.
Doggett: Call him Clark Kent.
When Scully and Doggett are discussing the possibility of X-ray vision Doggett mentions Clark Kent.
He is referring to Superman's alter ego. Superman is a fictional superhero who disguise himself as a news reporter by the name of Clark Kent.