it from a bridge. Despite Scully's pleas, Mulder jumps onto the top of the train as it speeds past below. Production Writing The idea to create a story involving the 731 unit came from series creator Chris Carter. He noted, "Unit 731 first came to my attention at the same time as it did for a lot of other people, when I read it in the New York Times about what the Japanese did to prisoners of war during the Second World War." Carter decided that an episode based around former war criminals who had received "clemency so [Americans] could use their science" would be "interesting". Frank Spotnitz was assigned writing duties for "Nisei", which was originally intended to be a stand-alone mythology story and to air as the seventh episode of the third season. However, as Spotnitz developed his script, the episode hit several logistical snags. Most notably, Spotnitz's script featured several scenes filmed on trains: Chris Carter explained, "We found that we were going to have some trouble shooting with trains." Eventually, the sheer scope of the episode caused co-executive producer R. W. Goodwin so much trouble that he wanted to scrap the story. Spotnitz explained, "Goodwin called Chris and said, 'This is unproducable. […] you've got to throw out the script, basically.' I was devastated, and Chris [said] 'Let's make it a two-parter.'" So, the episode was bumped back to number nine and was lengthened to a two parter, resulting in it being delayed several weeks. Filming A co-executive producer called this episode and its second part "731" logistically huge. The stunt where Mulder jumped on a moving train was worked on for six weeks. While there was some alarm in having David Duchovny do the stunt, the actor, who had previously performed his own stunts on an aerial lift in the episode "Ascension", was willing to do it and considered it a fun experience. The producers used trained rangers to play the soldiers in the teaser, part of an attempt to keep the show grounded in reality at all times. An 11-year-old boy was used to play the dead alien on the autopsy table. The boy's twin sister was used to play the alien on the train car. Both underwent extensive makeup including oversized dark contact lenses to create the effect of the alien eyes. After watching the video bought by Mulder, Scully criticizes it citing