Trivia: Whenever the Cigarette Smoking Man smokes on the show, the actor is smoking herbal cigarettes.
Trivia: Two numbers that appear frequently during the series are 1013 and 1121. October 13 is series creator Chris Carter's birthday, and November 21 is his wife's birthday.
Trivia: The Lone Gunman is a reference to the Kennedy assassination, in which the Warren Commission reported that a lone gunman, Lee Harvey Oswald, killed President John F. Kennedy. Ironically, Bruce Harwood's character, John Byers, is named after Kennedy.
Trivia: If the story in this episode is to be believed, Scully is now completely immortal. Alfred Fellig couldn't die because he had bypassed death - his nurse died in his place. When Scully is all but dead and Fellig grabs death away from her and dies himself, this should leave Scully in the same position as Fellig was before he died - completely immortal.
Trivia: The Cancer Man smokes Morley cigarettes, a fake brand that has appeared in a number of TV shows and movies since the '60s.
Trivia: Series creator Chris Carter changed the name of William B. Davis' character from "Cancer Man" to "Cigarette Smoking Man" about halfway through the series so tobacco companies wouldn't be offended. However, the character was still referred to by both names throughout the series.
Trivia: The shot of Tooms going down the chimney to reach his fourth victim was not done by any visual effects. A contortionist named Pepper actually squeezed inside, and then the sounds of bones cracking and snapping were added later. Confirmed by co-executive producer Robert Goodwin.