"Trials and Tribble-ations," one of Star Trek: Deep Space Nine's most-entertaining, most-ambitious and most-popular episodes, aired on November 4, 1996, or 20 years ago today. The episode, the sixth hour of DS9's fifth season, was created to celebrate Star Trek's 30th anniversary, employed CGI wizardry to morph together the characters -- and casts -- from Star Trek: The Original Series and DS9. And so we relished the sight of DS9 characters being yelled at by Kirk during a lineup of his crew and getting in on the action during the "Trouble with Tribbles" bar fight, and also Dax serving as the eyes and ears of the audience (and standing in for the writers and producers) as she soaked it all in as she traversed the Enterprise.

To celebrate the 20th annviersary of "Trials and Tribble-ations," we at StarTrek.com thought we'd share some facts, figures and anecdotes:

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Prior to settling on "The Trouble with Tribbles" as their entry point for the anniversary episode, the DS9 producers contemplated revisiting "Charlie X" and "A Piece of the Action."

The Temporal Investigations figures Lucsly and Dulmer boasts fairly unusual names. But if you happen to be a fan of The X-Files as well as Star Trek, you'll catch the in-joke. Lucsly and Dulmer are anagrams (or semi-anagrams) for Scully and Mulder.

One of our favorite lines: "I'm a doctor, not a historian," uttered by Bashir as he, O'Brien, Sisko and Dax bicker about fitting in.

Charlie Brill, who played Arne Darvin -- the Klingon posing as a cranky human -- in "The Trouble with Tribbles" was shocked to, 29 years later, receive a call from DS9 producer Ira Steven Behr about returning to the role for "Trials and Tribble-ations." Behr had recently seen, but not spoken to, Brill at a Beverly Hills pizza place, which compelled him to include Brill, and Darvin, in the "Tribble-ations" script. Behr called Brill and it was "completely out of the blue," Brill told StarTrek.com during a 2013 interview. "I had no idea. When they told me how they saw me in the episode, I couldn’t believe it. I was doing another series at the time called Silk Stalkings and I asked the producer if he could give me an episode off so that I could do DS9, and he said, “I can only give you three days off.” Ira told me had I given him more than three days the part would have been much, much bigger, but I couldn’t break away from Silk Stalkings to give them more than the three days. Still, it was the most fun I’ve ever had. To go on the Enterprise again was mind-blowing."

According to Memory Alpha, "Everything from the TOS sets was created faithfully right down to the blinking lights on the bridge, which the crew recreated by freeze-framing and painstakingly examining the TOS footage. Everything from the turbolift control panels to the wall intercoms to basic surface textures and back-lit graphics in the corridors were reproduced exactly as they originally appeared. Even the pattern of the overhead graphics in the Enterprise corridors is identical to the original."

This episode, at the time, was the most-expensive one-hour show produced.

Also, per Memory Alpha, "The clip featuring Sisko meeting Kirk was created with footage from "Mirror, Mirror" rather than 'The Trouble with Tribbles,' taking Kirk's introduction to the prime universe Marlena Moreau and inserting Sisko in Moreau's place."

Armin Shimerman plays Quark in the episode, but says nothing. It's the only episode in which the character appears but does not talk.

David Gerrold, who wrote "The Trouble with Tribbles," turns up in two "Tribble-ations" scenes.

Visitors to the set during production included Walter Koenig, Majel Roddenberry and Robert Justman.

Another great line, spoken by O'Brien: "I lied to Captain Kirk! I wish Keiko could have been there to see it."

Marvel Comics released "Nobody Knows the Tribbles I've Seen," a comic-book sequel to "Tribble-ations," in February 1998.

"Tribble-ations" earned a Hugo Award nomination for Best Dramatic Presention and was nominated for three Creative Arts Emmy Awards: Outstanding Special Visual Effects, Outstanding Hairstyling for a Series and Outstanding Art Direction for a Series.