 "Field Trip" was written by executive producer Frank Spotnitz, who described the writing process as "an experience". The script went through several phases; originally, the script was supposed to feature Mulder trapped in a cave with a mysterious monster. Then, the script was changed so that both Mulder and Scully would be trapped in the cave. Finally, the story was altered so that both Mulder and Scully only believed that they two were trapped in a cave, with only Mulder beginning to realize what was actually going on.
