"Memento Mori" was written in only two days, when previous series writer Darin Morgan did not contribute a script for the season. Discussion between the writing staff led to the "obligatory" decision to have Scully diagnosed with cancer, although the decision was not unanimous. Guest actor Lovgren portrayed multiple clones of his character using post-production techniques to merge several shots; while actor Pat Skipper had a scene cut from the final episode for time restraints, later appearing in the season finale.