Robert Patrick found this to be a particularly challenging episode but was thrilled at the opportunity. He has described it as his favorite episode.
Only the second X-Files episode to come with a viewer discretion warning because of graphic violence. Home (1996) was the first.
This is the first time that Doggett meets The Lone Gunmen.
Gillian Anderson was unavailable for most of this episode, so Doggett gets paired up with Skinner and The Lone Gunmen to cover her absence.
The character of Andre Bormanis is named after one of Frank Spotnitz's childhood friends André Bormanis who was a science consultant on Star Trek: Voyager (1995) and Star Trek: Deep Space Nine (1993).