The exploding pustules were carefully rigged to burst on command. Makeup supervisor Toby Lindala constructed a hand-held device that connected via tube to the faux sores. When the device was pressed, the pustule would burst.
The producers considered delaying the airdate of this episode as the movie Outbreak (1995) was just hitting theaters. Instead, they decided the episode could stand on its own two feet.
Producer R.W. Goodwin recalled how he knew that he was working on The X-Files (1993) when he overheard director Rob Bowman saying to make-up artist Toby Lindala, "I need the pus to go from left to right."
The speed limit sign near the gas station appears to show that the speed limit is 80 mph. However, the sign originally said 80 km/h: the "k" (kilometer) in "km/h" was whited out to hide that the show was actually filmed in Canada. Also, the gas station is located on a rural road; it is very unlikely that the speed limit on such a road in the USA would be 80 mph. (80 km/h equals 50 mph.)
One of the insects Dr. Robert Torrence has collected resembles the worms seen in season 1 episode "Ice".