In the writers and directors' guide for the series, written by Gene Roddenberry prior to the first season, Romulans were covered by one of the main writing rules which stated "No stories about warfare with Klingons and Romulans and no stories with Vulcans. We are determined not to copy ourselves and believe there must be other interesting aliens in a galaxy filled with billions of stars and planets." Following the perceived failure of the Ferengi as the main villains of TNG by the production staff, the Romulans became the main villains during the early years of the series. This was in addition to the Borg, who were originally developed as an insectoid race for this episode but became a race of cyborgs by the time they first appeared in Q Who (1989).
Maurice Hurley had something more in mind with this episode. The attacks the Romulans complain about dangled as an unresolved plot device for quite some time, but there was a plan: Hurley had meant this episode to compose part of a trilogy in which the Borg would be formally introduced. The opening episode of the second season further explored matters, including a possible alliance between the Federation and the Romulan Empire to counter the new threat. Such plans, however, were ruined by the 1988 Writers Guild of America strike. The Borg's introduction had to wait until Q Who (1989).
The subplot regarding the time-displaced characters was added at the last minute after the cliffhanger angles to the plot had to be scaled back. The subplot was based on a fan story written by Deborah McIntyre and Mona Clee.
This episode was a milestone in the history of Star Trek by establishing that the first season of TNG took place in the year 2364. This was the first time an exact calendar date was provided for a Trek episode. (Kirk's timeline had been established as the 23rd century in the movie Star Trek IV: The Voyage Home (1986).) All Star Trek episodes, chronologies, novels and background information since 1988 have been calculated from this date.
When Claire Raymond searches for her family members with Counsellor Troi, the names on the screen are the names of the series' main crew actors.