In this episode, Majel Barrett reprises her role of a ship's computer voice (in this case, voicing the Defiant's computer). Her inclusion here meant she had been credited as a performer in all six televised Star Trek series, and all five live-action versions. As well as playing several characters (such as Number One, Nurse Chapel, and Lwaxana Troi), she also provided the voice for the computers aboard USS Enterprise, USS Enterprise-D, USS Defiant (NX-74205), various runabouts, and the USS Voyager. This episode was the penultimate official Star Trek production that she worked on, later voicing the ship's computer aboard the USS Enterprise of the alternate reality, in Star Trek (2009). EDIT: Majel Barrett's voice was posthumously used in Star Trek Picard S3Ep9 and 10 as the computer voice of the Enterprise D, making that her last "appearance" in the franchise at the time of this update (10/12/23)
Whenever the Defiant's original (dead) crew are shown, their bodies are positioned identically to how they were shown in The Tholian Web (1968).
This was the first time in Star Trek history that the sets from The Original Series had to be rebuilt from scratch. The sets included the bridge and the hallway sets, as well as the Jefferies tubes. In Relics (1992), much of the bridge set was filled in through computer animation with some parts rebuilt, and in Trials and Tribble-ations (1996), footage from The Trouble with Tribbles (1967) and Mirror, Mirror (1967) were used.
The scene wherein Archer makes a lengthy spiel to a group of gathered officers was filmed on Wednesday, 2 February, 2005. During production on the scene, UPN declared that Enterprise was being canceled at the end of the season.
Vulcan crewman Soval wears a goatee. This is a nod to Mr. Spock in Mirror, Mirror (1967) where the Mirror Universe was introduced.