The scenes featuring shots of beetles crawling out corpses were shot and filmed using real insects as well as real actors.
Because David Duchovny and Gillian Anderson were busy in post-production on their self-penned directorial episodes, All Things (2000) and Hollywood A.D. (2000), the onus on the writers was to separate the agents as much as possible and reduce their screen time. So, Scully spends a lot of time in the autopsy bay and Mulder is hospitalized, leaving the field open for Skinner to steer the investigation.
The phrase that Weaver/Ashman keeps attempting to recite is "E Pluribus Unum" and is written in the logo of Marlboro brand cigarettes. The fictional cigarette brand "Morley" shares many aesthetic similarities with Marlboro. The phrase translates to "Out of many, one" and is also the national motto of the United States of America.
To suggest the harmful effects of tobacco, the color schemes used in this episode are largely brown and off-yellow.
The fictional tobacco company, Morley, is the same brand of cigarettes that CGB Spender has smoked throughout the series.