 Gordon and Greenwalt were also assisted by fellow writers Ken Horton, John Shiban, and co-executive producer Frank Spotnitz.A few days before filming was slated to begin, Gordon was still frantically reworking the teleplay; during these last-minute rewrites, he removed a number of elements, including two "useless characters" (one of whom was a Stephen Hawking-esque scientist in a wheelchair)a move that he claims "really tightened up the story".David Duchovny later revealed that a few of the episode's scenes were even written during filming "because no one could know if the audience understood what was happening".