It was an early episode. They didn’t have a crew yet. Or shuttlecraft.
Hey, Neelix was annoying, but Tuvok was cool. Especially that time when he went all Die Hard villain on the Enterprise-D.
I always liked Sulu’s line as night began to fall: “It’s getting a little nippy down here!” 
(Of course, knowing what I know now, that line can also take on an entirely different hue… :rolleyes: )
In the films it was, and so I’m assuming in the play, if the scene exists. In the book it’s precipitated by hubris.
And in the combing the desert scene in “Spaceballs.”
“We ain’t found shit!” 
Any story whose central theme is duality of personality (aren’t they all?) will appear to copy JaH because that is the contemporary standard. But RLS didn’t create the idea, so he too must have copied someone. To say something like the episode in the OP is a direct mimic of RLS is narrowing things a bit.
Actually, I just watched the episode last night, and the fact that EKirk demands alcohol as his first act, and then starts bothering a particular woman until she starts to feel terrorized makes me feel like it very much parallels the Hollywood films that rely heavily on the Sullivan play, which was written just a year or two after the book was published, and IIRC, the blessing of RLS.
In all three movies, the first “Hyde” thing Dr. Jekyll does in go to a music hall/tavern, and get plastered. In the Barrymore film, he is still Jekyll, but he is very strait-laced, and yet has a great time, and is therefore motivated to create his transforming potion so he can go out and drink, swear, and fool with loose women* without ruining Dr. Jekyll’s reputation. In the other two films, he is already Hyde, and had met a woman as Jekyll, she made a pass at him, he refused, and so as Hyde, he sought her out in the establishment.
GKirk literally restrains EKirk in the ep, the way that Jekyll in the film tries to restrain Hyde, but Hyde overcomes him, just like EKirk overcomes GKirk, and it happens when both the good guys let their guard down. GKirk does it literally; Jekyll does it figuratively, by thinking that the Hyde part of his life is over.
I think there are deliberate parallels. They could be more obvious, if the episode were intended to be nothing other than a copy of the Jekyll & Hyde story. Clearly Matheson used J&H as a springboard, not an outline, but he is familiar with the Hollywood films, and probably the Sullivan play, I’m guessing.
One big difference is that lack of any Faustian elements, but I suspect that would be out of character for Kirk.
*100 points for reference
Kirk ordered the corridors cleared, obviously.
But only Evil Kirk could make that kind of command decision. :o
Fine. SPOCK ordered the corridors cleared.
Or, Spock used Vulcan mind control to make wimpy Kirk say it.
[Voice of Sheldon Cooper]: Excuse me, but in what universe is Spock a Jedi knight?!? :dubious:
I think they did this when they moved from Sick Bay to the Transporter Room. But hey, how many times can you get away with it before someone catches on? :dubious:
Only once, if that.
But so what? It’s not a pleasure liner; it’s a military (okay, naval) vessel. The crew does what they’re told, in general.
And clearly some people had to be in the know anyway. I’m sure Kirk or Spock explained things to Rand.
Not fully, though. Didn’t Kirk say, “The imposter’s back where he belongs,” and just leave it at that?
Plenty of conversations happen off-screen yet may reasonably be inferred to occur. There’s no scene in “Amok Time” where McCoy explains to Chapel or Scotty why he beamed up with an apparently dead captain who was alive 10 minutes later, but it surely happened. There’s no scene when Kirk and Spock say to Chekov, “Yes, we realize you’re the navigator, but you’re clearly also the second-best person on board at using the science station, so any time you’re on the bridge and Spock is called away from that station, you automatically relieve him,” but that also is clearly implied.
Ah, like the time Chekov ran into Khan on the Enterprise.
That complaint, if you’re serious, always irks me. It’s canon that there were 430-some persons in the Enterprise’s crew, and clearly we only see a tiny fraction of them. There’s no episode introducing Chekov to the crew. Chekov could easily have been working the midnight shift when Khan was on board, and Khan simply remembered his face and name because he remembers EVERYTHING.
To me, the ST plot line bears more resemblance to the Italo Cavino story: the Cloven Viscount (although that story owes something to RLS too).
In Jekyll and Hyde, neither of the “TWO” characters is ineffectual. In both the Calvino story and the ST plot line (which I haven’t seen for some time) each “half” of the character is missing something of the other and is ineffective because of it.
Chekov could’ve been promoted to bridge crew from another Ent assignment (suggested at a Con)