The Trouble With Tribbles - S2-E15
Trivia: The intention of introducing the Klingon Capt. Koloth was to bring in a counterpart and recurring adversary for Kirk, but that intention was never carried out.
Trivia: The title "Return to Tomorrow" didn't translate well into other languages. So in France, the episode became "You Are Nothing But Dust"; in Japan, "Energy at 160 Kilometers Underground," and in Germany, "Ghost Craves Body!"
A Taste of Armageddon - S1-E24
Trivia: The doors and walls of Eminiar 7 are exactly the same as the doors and walls of the Imorg in "Spock's Brain" save for new colors of paint.
Trivia: The title is taken from Macbeth Act 5, Scene 5.
Trivia: The front of the Ekosian Chancellery is an actual office building of Paramount Pictures.
Who Mourns for Adonais? - S2-E2
Trivia: The hand seen stopping and holding the Enterprise is Gene Roddenberry's.
Trivia: Leonard Nimoy is the only actor to appear in all 80 episodes (including the pilot) of the original series.
What Are Little Girls Made Of? - S1-E8
Trivia: The phaser weapon that Brown, then Andrea, used was from the pilot episode with Captain Pike.
Shore Leave - S1-E16
Trivia: Because Theodore Sturgeon's original script for "Shore Leave" was so complex, many scenes were too expensive to film. Gene Roddenberry had to hastily rewrite many of these minutes before they were shot, resulting in some segments that were ad-libbed because the rewrites hadn't been completed. McCoy's "distracted" scene with Yeoman Barrows is one of these.
Trivia: In the 1960s, showing the female navel was forbidden by NBC's censors. This was why Losira's costume had that weird square patch sticking up from the otherwise low-cut hip-hugger pants. (Oddly, no such restriction applied to male costumes.) By 1969, the network had abandoned the rule, and "The Cloud Minders" became the only Trek episode with costumes shamelessly exposing women's navels.
The Enterprise Incident - S3-E2
Trivia: The third season's tight budget forced the recycling of many props. Here, the Romulan cloaking device was rather obviously cobbled together from two items used in previous episodes: Nomad's head from "The Changeling," and Sargon's globe from "Return to Tomorrow."
The Corbomite Maneuver - S1-E11
Trivia: After Kirk leaves Sickbay, and after McCoy says one of his "What am I...?" questions (i.e., I'm a doctor, not a _______), he says, "If I jumped every time a light flashed around here, I'd end up talking to myself." Later, in Star Trek V, as he's watching Kirk climb the mountain, he says, to himself, "'You'll enjoy Shore Leave. You'll be able to relax'. You call this relaxing? I'm a nervous wreck. If I'm not careful, I'll end up talking to myself."
The Trouble With Tribbles - S2-E15
Trivia: According to the screenwriter David Gerrold, the producers of the show noticed a similarity of the plot line and story concept to Robert A. Heinlein's story "The Rolling Stones" and asked Heinlein for permission to use the idea. Heinlein asked for an autographed copy of the script, but otherwise did not object, noting that both stories owed something to the Ellis Parker Butler's 1905 short story "Pigs is Pigs" and perhaps "Noah". (Source "The Trouble With Tribbles: the birth, sale and final production of one episode" by David Gerrold).
The Corbomite Maneuver - S1-E11
Trivia: The voice of the Balok puppet in this episode is Ted Cassidy, who played Lurch in "The Addams Family". Cassidy had previously starred as Ruk in the episode "What Are Little Girls Made Of?"
Trivia: Phil Morris, son of the actor Greg Morris, appears as a boy in this episode. He would later go on to star in the feature film "Star Trek III: The Search for Spock" as well as "Star Trek: Deep Space Nine" and "Star Trek: Voyager".
Trivia: Director Marc Daniels employed an old trick to save Nona's topless bathing scene from NBC's censors. He deliberately shot twice the needed footage, including risque side shots exposing portions of bare breast. After the censors excised the "most naked" portions, what remained was precisely what Daniels had wanted to begin with: a bare-backed Nona bathing in the waterfall.
Answer: Kirk was getting his physical and Dr. McCoy probably turned off communications, because if he hadn't, Kirk would have left and headed straight for the bridge, leaving McCoy irritated.