Wade Davis is mentioned in this episode. He wrote "The Serpent and the Rainbow" based on his experiences in Haiti. That book inspired the film The Serpent and the Rainbow (1988) with similarities to this episode.
Callum Keith Rennie's second appearance in the series, playing a groundsman in a cemetery. He had previously appeared as the brother of a bank robber in Lazarus (1994). This doesn't mark the end of Rennie's involvement in the franchise - he would appear as one of the villains in the second feature film The X Files: I Want to Believe (2008).
This episodes marks Roger Cross' second appearance as military personnel in the series. He appears a total of 5 times in the series, each time portraying a different character, either military or government agents.
The shot of the highway Mulder and Scully are driving on in the beginning, labeled as "County Road 10, Folkstone, North Carolina", is the same shot used in "Aubrey", three episodes earlier, for the road labeled "Highway 377 near the Missouri/Nebraska border".
One of the first examples in the series in which Scully drives the agents around. Usually, it's Mulder in the driving seat.