the Federation and that a planet called Archer IV that had previously appeared in Star Trek: The Next Generation was in fact named after him. Casting The episode saw the return of Vaughn Armstrong as Captain Maximilian Forest. His main universe character, Rear Admiral Maxwell Forest, had been killed earlier in the season in the episode "The Forge". Both Bakula and Armstrong joked about the character suffering two deaths during the same season, although Armstrong also said of the relationship between mirror-Forrest and mirror-Hoshi that "in 25 years [of acting], I haven't gotten the girl, but I come back here and I get the girl! This is great." Gary Graham returned as the Vulcan Soval, who was a science officer aboard the Avenger in the mirror universe rather than his normal position of the Vulcan Ambassador. Graham was given a goatee beard in reference to the mirror universe Spock from "Mirror, Mirror". Other guest stars in "In a Mirror, Darkly" included Gregory Itzin, who had previously appeared as a Vulcan commando in "Shadows of P'Jem" as well as episodes of Star Trek: Voyager and Deep Space Nine. Derek Magyar returned for his third appearance as Kelby after previously appearing in "Affliction" and "Bound". Writer Mike Sussman also appeared on screen, as one of the dead Defiant crew-members. With this episode, actress Majel Barrett, widow of Star Trek creator Gene Roddenberry, became the only actor to participate in every Star Trek series, including the animated series, as well as both the Original Series-based and Next Generation-based film series. In this episode, she provided the voice of the starship Defiants computer. Her voice continued to be used as that of Starfleet computers after the cancellation of Enterprise in the J. J. Abrams led Star Trek films. These installments saw significant changes to the characters of the main cast. Linda Park, who plays Hoshi Sato in the series, later said that they were her favorite episodes of the show. She later explained: "Mirror Hoshi was strong in the way that Medea is strong, in the way that Clytemnestra is strong, in this very archetypal, warrior-woman way." She credited the role she played in this episode as demonstrating that she could play a tougher character, something which allowed her to gain other roles once the series ended. Connections The Gorn featured in this episode, was previously introduced to the Star Trek science fiction universe