Mulder, Scully and the Cigarette Smoking Man are the only characters to appear in both this episode and the series pilot nine years ago.
Lucy Lawless was originally slated to appear as Shannon McMahon. However, Lawless was experiencing a high-risk pregnancy and was unable to return to the show.
Most of the cast and crew found the final scene between Mulder and Scully very difficult to get through due to how emotional it was for all concerned.
With 13.25 million viewers, this was the most watched episode in Season 9.
This marks Laurie Holden's first time appearing in the show since the Season 7 finale, Requiem (2000).