According to John Shiban, Mulder was not supposed to wear Dracula's mask, but he asked to because Dracula was one of his favorite characters as a child.
Kate Braidwood, who plays the movie theater usher, is the daughter of X-Files first assistant director Tom Braidwood.
The title refers to the Pine Bluff Arsenal, a military installation in Jefferson County, Arkansas that was known to house chemical weapons.
That's not the real Capitol Building seen in the teaser. This scene was actually shot in Vancouver with the Capitol being digitally dropped in to the background.
The theater in Ohio has Die Hard with a Vengeance (1995) as the feature film. The musical score of this episode departs from the usual X-Files standard spooky (or silly, if it's a humor episode) fare and creates a very tense and foreboding edge-of-your-seat atmosphere using French horns. The tempo and style are remarkably similar to the score of the Die Hard movies, especially the one referenced.