Alexander Siddig was producer/creator Rick Berman's first choice to play Benjamin Sisko, but he was eventually deemed too young. Instead, he got the role of the genetically-enhanced Julian Bashir.

Among the actors to read for the role of Captain Sisko was Eriq La Salle who would later be cast as Dr. Peter Benton in ER. James Earl Jones and Tony Todd were also offered the role.

Among the finalists for the role of Sisko was Gary Graham, best known for the TV series Alien Nation.

Kira was a last-minute addition to the cast; the original plan was to include the Star Trek: The Next Generation character of Ro Laren, but Michelle Forbes didn't want a series at the time.

The role of Jadzia Dax was initially offered to Famke Janssen. Both she and Michelle Forbes (see above) turned down the roles in order to remain available to appear in feature films.

The character that eventually became Vic Fontaine was written for Frank Sinatra Jr.. in Season 4. Sinatra, despite being a fan of the show, turned it down, declaring that he only wanted to play an alien. After meeting with Robert Goulet, and attempting to get Steve Lawrence, Tom Jones and Jerry Vale, the producers eventually decided on James Darren in Season 6. Darren would go on to appear in 8 episodes, including the series finale.

Dax was originally envisioned as an alien from a low-gravity world forced to get around in a wheelchair and who flew around her quarters; the concept was scrapped and recycled into the character of Melora because the "flight" cables were too difficult to rig.

The spots on Jadzia Dax were not stenciled. Instead, they were drawn on personally by Michael Westmore each day, a process which took over an hour.

In the episode Trials and Tribble-ations, Crew from Deep Space Nine are hijacked into the episode "Trouble with Tribbles" The set of the original Enterprise was re-created for this episode in detail except for the orange grating often seen in engineering areas. Apparently, the company that made it had discontinued its production.

After production ended and the sets were dismantled, the Defiant bridge set was declared "fold & hold" and placed in storage. It has been redressed and reused as the bridge of an alien cargo ship and a Klingon battlecruiser on Star Trek: Voyager (qv) and the bridge of the ECS Fortunate on Star Trek: Enterprise.

In the episode "Man Alone," the planet Alderaan is listed as a recent place visited by a murder victim. Alderaan is the planet destroyed by the Death Star in Star Wars.

Stars Alexander Siddig and Nana Visitor were married in real life in 1997 (after the show's fourth season).

The subplot of Kira carrying the O'Briens' baby was to explain away Nana Visitor's pregnancy.

The only characters who appeared on this series before they appeared on Star Trek: The Next Generation are: Quark (Armin Shimerman), Dr. Julian Bashir (Alexander Siddig) and Gul Evek (Richard Poe) All other characters who appeared on both shows (Chief O'Brien, Worf, Captain Picard, Q, Lwaxana Troi, etc.) appeared on The Next Generation first.

Martin Sheen was considered for the role of Sloan, the Section 31 operative.

Avery Brooks (Commander/Captain Benjamin Sisko) is the only actor to appear in every episode of the series.

Jeffrey Combs portrayed both the Ferengi character Brunt and the Vorta administrator Weyoun throughout most of the series' run, making him the only actor on any Star Trek series to play two recurring roles on the same series (not counting the animated series). The only episode to feature both Brunt and Weyoun was the next-to-last episode "The Dogs of War". Prior to playing either role Combs played another character, Tiron, a wealthy alien attracted to Kira, in the third season episode "Meridian"

The only characters who appeared on this series before they appeared on Star Trek: The Next Generation are: Quark (Armin Shimerman), Dr. Julian Bashir (Alexander Siddig) and Gul Evek (Richard Poe). All other characters who appeared on both shows (Chief O'Brien, Worf, Captain Picard, Q, Lwaxana Troi, etc.) appeared on The Next Generation first.

References are frequently made to Starfleet "ground troops," and some Starfleet characters have different uniforms (a black uniform with a small colored stripe across the middle). Fans generally accept that these characters are part of a Starfleet Marine Corps, although this has never been explicitly stated onscreen. There was a Starfleet Colonel West in Star Trek VI: The Undiscovered Country (1991); West was most likely a Starfleet Marine, since navies do not have the rank of colonel.

Reportedly, Gene Roddenberry was made aware of plans for Star Trek: Deep Space Nine not long before his death in 1991, making this the last Star Trek TV series that he was connected with.

The number 47 pops up an inordinate amount of times on computer screens, serial numbers, dates and so on. This tradition was started by writer/coproducer Joe Menosky and was soon picked up by the rest of the production team. Menosky said that he choose that particular number because when he was a graduate student at Pomona College, Professor of Mathematics Donald Bentley proved as a joke that all numbers are equal to 47. Interestingly, the later series "Alias" also featured the number 47 many times, and incorporated it into its ongoing storyline.

In the 5th season episode "Trials and Tribble-ations" the names of the Federation temporal investigators "Dulmer" and "Lucsly" are anagrams of "Mulder" and "Scully" from The X Files.

The Star Trek ranking systems are all based upon actual human ones. The Starfleet ranks are those of the US Navy (specifically the US Navy, the British Royal Navy has similar ranks but they do differ slightly). Bajor and the Klingon Empire both use the ranks of the US Army/Air Force. And it is a little-known fact that the Cardassian ranking system is in fact based upon that of the ancient Roman Empire - Legate, for example, was a rank just below General in the Roman military.

Andrew Robinson, who plays Garak, was originally intended to play Odo. However, the producers decided to go with 'René Auberjonois' , instead.

People close to J. Michael Straczynski, the creator of Babylon 5, claim he contacted Paramount with his idea for a show about an interstellar space station as he knew Paramount was the only big production company with a long tradition in science-fiction. The people at Paramount turned it down and Straczynski continued his search for a money-strong production company. Not long after Paramount announced the plans for Star Trek: Deep Space Nine, a show strangely similar to Babylon 5. In the opening of "The Assignment", Chief O'Brien ('Colm Meany' ) mentions the the name "G'Kar", which was the name of one of the principal characters of Babylon 5, which could lend credence to this possibility.

The guy who is often in Quark's bar is named "Morn", which is an anagram for "Norm" from Cheers, who was often in the bar.

The uniforms initially worn on Star Trek: Deep Space Nine were designed to look different from those worn on its parent show, "Star Trek: The Next Generation" Beginning with the movie Star Trek - Generations, however, these new uniforms were adopted by the Star Trek: The Next Generation crew and Starfleet as a whole.

In one episode, while Kira is still pregnant the O'Briens' baby, she screams at Dr. Bashir (Alexander Siddig) "This is all your fault!" This is an in-joke referring to the fact that actress Nana Visitor and Siddig were expecting a child in real-life.

According to an April 2003 interview, Avery Brooks was initially required by contract to appear with hair in order to prevent confusion with his Spenser: For Hire character, Hawk. In later seasons, as Sisko became established, Brooks was allowed to shave his head and re-grow his beard.

The square glasses used in Quark's bar are actually candle holders turned upside down.

Although we only rarely see it, there is an ATM in Quark's bar. It dispenses the various types of currency used by major races visiting the station: Federation credits, Bajoran litas, Cardassian leks, and Ferengi latinum.

Armin Shimerman was a regular on both this series and "Buffy the Vampire Slayer" at the same time.

In a scene where Bashir and O'Brien come out of the holo-suite and talk to Quark dressed as WWII RAF pilots, most of O'Brien's jargon comes from a Monty Python sketch, RAF Banter.

In the Klingon military, the officer rank system is organized like this: Ensign, Lieutenant, Commander, Captain, Colonel, Brigadier, General. There is also a 'bekk', which is an enlisted rating.

The Bajoran officer ranks are the same as those used in the US Army, Air Force, and Marines: 2nd lieutenant, 1st lieutenant, Captain, Major, Lt. Colonel, Colonel, General. (Kira, after her promotion, was referred to simply as 'colonel', but this is normal even for officers with the actual rank of Lieutenant Colonel.) Cardassian ranks - that we know of - are Gil (equivalent to a Starfleet naval lieutenant), Glinn (commander), Gul (captain), Legate (admiral).

The tankards used for Klingon bloodwine are actually measuring cups used in baking.

Buck Bokai, a baseball player of the 21st Century, broke Joe DiMaggio's record for consecutive hits in 2026. While the name is never mentioned, this fact is mentioned in the Star Trek: The Next Generation episode "The Big Goodbye."

Buck Bokai's baseball card, a collectable featured on Benjamin Sisko's desk, had actor Keone Young on the front, in character, but showed "Trek" model maker Gregory Jein, who invented the "history" of the character, on the back. The pair bore an uncanny resemblance to each other.

In the episode "Homefront," Sisko notes the names of some of the officers whom he served with on the U.S.S. Okinawa: Daneeka, McWatt, Snowden, Orr, and Moodus. All of these are the names of characters in Joseph Heller's book "Catch 22".

Mark Allen Shepherd, in addition to his regular role as Morn, appeared as a Bajoran officer (whom Quark asks to sit in Morn's usual place at the bar) in the episode "Who Mourns for Morn?".

The design of Ops incorporates ideas that were considered but dropped for The Bridge on Star Trek: The Next Generation, such as the upper level office, the briefing table in the center of the room, and the transporter being built into the set.

The Bajoran monetary system uses the Lita as currency. The Lita is actually the name of the currency of Lithuania.

The character Elim Garak is a former spy who works as a tailor on the station. In many of John le Carré's spy novels a tailor is one of the main characters (and is often also acting as a spy). "The Tailor of Panama" and "Tinker, Tailor, Soldier, Spy" are two examples.

Malcolm McDowell once said he'd like to appear on Star Trek: Deep Space Nine, but only if his nephew - Alexander Siddig (who plays Star Trek: Deep Space Nine's Dr. Bashir) - would direct the episode. Unfortunately, this never panned out, mostly due to scheduling conflicts.

Wolf 359, mentioned as the battle site where Sisko lost his wife, is a real star that is 7.6 light years from Earth.

On occasion, sets from Star Trek: Voyager are used as other Starfleet locales. (For example: a holosuite grid in the episode "Inquizition", the entire U.S.S. Bellerophon [which was an Intrepid-class starship just as Voyager is] in the episode "Inter Arma Enim Silent Leges.")

The character 'Benjamin Sisko' was ranked 50 in TV Guide's list of the "50 Greatest TV Dads of All Time".

The 'Star Trek Crews' from all the Star Trek series were ranked 2 in TV Guide's list of the "25 Greatest Sci-Fi Legends".

In "The Dogs of War", the USS Sao Paolo is assigned to Cpt. Sisko as replacement for the destroyed USS Defiant. The ship's insignia names some of the Deep Space Nine creative staff as the constructors of this ship.

Sisko's middle name is Lafayette.

Continuity error: In "Take Me Out to the Holosuite", the name on the baseball shirt that Colonel Kira is wearing changes from "Kira" to "Nerys" throughout the game.

Continuity error: In "Dramatis Personae", Sisko throws away his communicator badge to escape the sensors. Later in the cargo bay, it's back on his chest.

Revealing mistake: In "Sanctuary", Haneek walks through an airlock and supposedly on to her ship. You can see the actor's reflection in the door, trying to get off-camera.

Revealing mistake: In "The Sons of Mogh", Kurn's prosthetic nose comes loose from his Kingon make-up. When he talks in the infirmary, you can see it wiggle freely.

Revealing mistake: Gowron's robe disappears after he announces Quark and Grilka's wedding is official in "The House of Quark".

Continuity error: Because the Trill spots on Jadzia Dax and Ezri Dax were painted anew by hand in the makeup department every morning of filming, and each set was unique, they change from episode to episode and even scene to scene.

Revealing mistake: In "A Simple Investigation", while Odo is talking to Arissa in his quarters. Through the window you can clearly see the edge of the star-field screen and floor it's resting on.

Revealing mistake: In "Broken Link" as Worf and Garak are fighting in the Jeffries tubes, a door to a Jeffries tube is knocked open and an unused area of the set can be seen behind it.

Factual error: In "Rules of Acquisition," the originally-aired version spelled the word "Acquisition" without the "c" and it appeared in the credits as "Aquisition." Also, the actress Hélène Udy's name was spelled incorrectly as Hêlene. Both goofs have been corrected in the DVD versions.

Continuity error: In "It's Only a Paper Moon", when the Star Trek: Deep Space Nine officers discuss Nog's recovery/state of mind, after he moved in with Vic Fontane, Lt. Ezri Dax' insignia change position. In the first three shots of her, the full one is on the left side of the black one. In subsequent shots they take their correct position. (Normally the full insignia are to the right of the black ones, which serve as a "placeholder" for future promotions.)

Factual error: In "Q-Less", the operations crew tries to track the power drain by releasing tritium gas into the station's atmosphere. It is frequently mentioned that tritium is extremely toxic. However, tritium is simply a heavy form of hydrogen, which is not toxic even in fairly strong concentrations, provided there is oxygen present for people to breathe. The principal danger in a case like this is from igniting the oxygen-hydrogen (i.e. tritium) mixture, not from poisoning the station inhabitants.

The opening credits for "Emissary" lacked the wormhole opening that all future episodes featured.  Starting with Season 4, the opening credits included additional spacecraft and activity around the station, including the Defiant flying into the wormhole.

“Emissary”, “The Way of the Warrior” & “What You Leave Behind” were originally 85 minute TV movies . Each TVM was later edited into two parts for syndication.