"Crossover" is the 43rd episode of the science fiction television series Star Trek: Deep Space Nine, and the 23rd episode of the second season. This episode was written by Peter Allan Fields and Michael Piller, and directed by David Livingston. It aired on broadcast television on May 16, 1994.
Set in the 24th century, the series follows the adventures on Deep Space Nine, a space station located adjacent to a stable wormhole between the Alpha and Gamma quadrants of the Milky Way Galaxy, near the planet Bajor. In this episode, first officer Kira and Doctor Bashir have an adventure in Star Treks Mirror Universe, a parallel universe setting introduced in the episode "Mirror, Mirror" of the original Star Trek series.
The mirror universe version of Odo wears a belt on his uniform. Rene Auberjonois liked the effect so much that he began wearing the belt while playing regular Odo as well.
Reception
A 2015 binge-watching guide for Star Trek: Deep Space Nine by Wired recommended not skipping this essential episode.
In 2016, The Hollywood Reporter rated "Crossover" the 78th-best episode of all Star Trek episodes. They note that this episode references the events in the Mirror Universe that occurred in the episode "Mirror, Mirror" and that this enhances the episode.
In 2017, SyFy ranked this the second best Mirror Universe episode of Star Trek of the seven that had aired at the time.
In 2020, io9 listed this as one of the "must-watch" episodes of Star Trek: Deep Space Nine.
In 2020, the U.K. science fiction magazine and website SciFiNow ranked this one of the top ten episodes of Star Trek: Deep Space Nine, noting that actress Nana Visitor seemed to have fun playing her evil twin from the mirror universe.
Releases
This was released on VHS with "Collaborator" on one VHS cassette, Star Trek: Deep Space Nine Vol. 22 - Crossover/The Collaborator.
On April 1, 2003, Season 2 of Star Trek: Deep Space Nine was released on DVD video discs, with 26 episodes on seven discs.
This episode was part of the Alternate Realities Fan Collective, and included a commentary by episode director David Livingston.
This episode was released in 2017 on DVD with the complete series box set, which had 176 episodes on 48 discs.