 "Letters of Transit" was co-written by consulting producer Akiva Goldsman and executive producers / co-showrunners Jeff Pinkner and J.H. Wyman. Although it was previously reported Goldsman would be directing, executive producer Joe Chappelle ultimately directed the installment. The Observers are prominently featured in the episode, a mythos that has been visible since the pilot. Previously a mysterious background presence, according to Noble, they have now become "incredibly centrally important" to the series'storyline. "Letters of Transit" was written and shot before the series' renewal for a fifth season, but it was always envisioned as a genesis of the season. During this time, Wyman confirmed that a majority of the fifth season would be set in 2036, following the events of this episode, a time period depicting the Observers as oppressors rather than as passive witnesses.
