television series Space: Above and Beyond, Carter called the series' creators Glen Morgan and Wong—who had previously been writers for the first two seasons of The X-Files—and asked if they wanted to rejoin the series. Morgan told Carter that the two of them would rejoin, but only for four episodes, and only if they could use members from the cast of Space: Above and Beyond, so that "the world can finally see them". Carter accepted this condition, and the two dutifully provided four of the seasons episodes. Filming The season finale, "Gethsemane", was notable in that an entire set created to emulate icy caverns was constructed inside a warehouse which had previously been used for cold storage; and required the use of truckloads of lumber and of Styrofoam. The set would become one of the most expensive and elaborate built during the series' history. The set required a constant temperature of in order to maintain the real snow and ice used to decorate it. This refrigeration allowed the actors' breath to visibly fog up, and allowed the cast to "have a place that feels real" to aid their acting. The outdoor scenes for the episode were filmed around Vancouver's Mount Seymour, with weather conditions making shooting difficult enough to require an extra day of work. Although the series' 1998 movie would take place after the events of the fifth season, the movie was actually filmed in the hiatus between the show's fourth and fifth season and re-shoots were conducted during the filming of the show's fifth season. Crew Series creator Chris Carter also served as executive producer and showrunner and wrote eight episodes. Howard Gordon continued as executive producer and wrote five episodes for his final season on the series. Spotnitz was promoted to co-producer and wrote seven episodes. Vince Gilligan was promoted to co-producer and wrote five episodes. Former X-Files writers Glen Morgan and James Wong returned after a one-season absence from the series as consulting producers and wrote three episodes together, with Morgan writing an additional episode solo that Wong directed. John Shiban was promoted to story editor and wrote four episodes. David Greenwalt joined mid-season as co-executive producer and wrote one episode for his only season on the series. Writing team Valerie and Vivian Mayhew wrote one freelance episode. Executive producer and frequent series director R. W. Goodwin wrote his first and only episode for the series.