First episode produced of season 3, although its airing was held back.
The word "sheriff" on the sign outside the sheriff's office is written in the same font as used in the opening and closing credits.
The voice of the Melkotian buoy was provided by James Doohan (Scotty).
For the third season of TOS, the series title and credits are now in a light blue color.
This is TOS's only foray into surrealism, with some truly unique set designs by Matt Jefferies.
Mike Minor designed the Melkot mask.
This is the only episode to end with the Enterprise heading toward a planet.
A very subtle change in the third season was the use of new sound effects for the pushing of buttons on the bridge.
Another difference this episode brings is the "singing plant" background noise from "The Cage", used for nearly every planet in seasons one and two, is replaced here by a new, warbly sound. This will be used intermitently throughout season three, in "For the World is Hollow and I Have Touched the Sky", for example.
James Doohan intensely disliked the hairstyle he debuted in this episode, which was not his own choice. By the filming of "The Tholian Web", this hair-do is gone for good.
This is one of three episodes ("The Man Trap" and "The Changeling" are the others) to indicate Uhura is of something other than African-American descent, as her native language is "Swahili". The writers' bible confirms she is from "The United States of Africa".
The scene from "Spectre of the Gun" of Spock mind-melding with Kirk, McCoy and Scott was originally going to be incorporated into Star Trek V: The Final Frontier.
DeForest Kelley himself played an Earp in the 1957 movie Gunfight at the O.K. Corral. He played Morgan Earp, starring with Burt Lancaster and Kirk Douglas. He also played Ike Clanton in a 1955 episode of You Are There.
Melkotian: Our warning was plain. You have disregarded it. You shall be punished. You, Captain Kirk, the disobedience was on your orders. Yours is the responsibility. Yours shall be the pattern of your death.
Kirk: We come in peace. But we'll defend ourselves if necessary.
Melkotian: You are outside. You are disease. The disease must be destroyed. Your plea has been heard, and sentence has been pronounced. It is done.
Johnny Behan: I knew you wouldn't let them scare you away. They're a bunch of hot air.
Spock: Are they really?
Kirk: You know us?
Johnny Behan: Funny. That's what I like about you, lke. You always see the funny side.
Kirk: I'm a barrel of laughs.
Spock: Captain, since we have seen that death is the one reality in this situation, I seriously suggest you reseat yourself immediately without moving a muscle of either hand. If I remember correctly, that would involve you in what was called, "the fast draw." It initiated unfortunate events.
Ed: You boys want your usual?
Scotty: Absolutely. Half a gallon of scotch.
Ed: You know we only got bourbon, unless you want corn whiskey.
Kirk: Mr. Spock, except for our hand guns, we haven't changed, not even our clothing, yet these people see and hear us as the Clantons.
Chekov: I don't think that's such a bad thing.
Spock: The day is still young.
Chekov: What can I do, Captain? You know we're always supposed to maintain good relations with the natives.
Kirk: I'm not Ike Clanton!
Ed: It's okay with me, Ike. Anything you say. Don't make no difference who I think you are. Your problem is, who does Wyatt Earp think you are?
McCoy: What's the matter?
Kirk: What do you call that stuff -- fire?
McCoy: "Taos Lightning --" straight bourbon. Try some. In small amounts, it was considered medicinal.
Kirk: Label it "For External Use Only".
Scotty: It just takes a bit of getting used to, Captain. Actually, a man could grow quite fond of this stuff.
McCoy: Take it easy. I hate to think what that stuff's doing to your stomach lining.
Kirk: We have to find a way to put the Earps out of action. Is there anything that exists here that could help us?
Chekov: All those western cossacks had were poisonous snakes and cactus plants.
Spock: Gentlemen, there is one thing which requires the immediate attention of all of us--specifically, our future.
Kirk: But not this minute, Spock. It takes us... a little longer.
Spock: I understand the feeling, Captain.
McCoy: You talk about another man's feelings. What do you feel, Spock?
Spock: My feelings are not subject for discussion, Doctor.
McCoy: Because there are no feelings to discuss!
Scotty: Chekov is dead! I say it now, and I can hardly believe it, but you worked closely with him. That deserves some memorial.
McCoy: Spock will have no truck with grief, Scotty. It's human.
Kirk: Bones... Scotty...
Spock: Captain... it's quite all right. They forget I am half human.
(Scotty takes a drink)
Scotty: It's to kill the pain.
Spock: But this is painless.
Scotty: Well, you should've warned me sooner, Mr. Spock.
Spock: I know the bullets are unreal, therefore they cannot harm me.
Kirk: We must all be as certain as you if we're to save our lives.
Kirk: But that's not possible. There'd always be some doubt. The smallest doubt would be enough to kill you.
McCoy: We're just human beings, Spock. We don't have that clockwork ticker in our head like you do. We can't turn it on and off.
Kirk: We must.
Melkotian: Captain Kirk...you did not kill. Is this the way of your kind?
Kirk: It is. We fight only when there's no choice. We prefer the ways of peaceful contact. I speak for an alliance of fellow creatures who believe in the same thing. We have sought you out to join us. Our mission is still one of peace.
Spock: This afternoon, you wanted to kill, didn't you?
McCoy: But he didn't kill, Mr. Spock.
Spock: But he wanted to, Doctor.
Kirk: Is that the way it seemed to you?
Spock: Yes, Captain.
Kirk: Mr. Spock... you're absolutely right. That's exactly the way it was.
Spock: Mankind... ready to kill.
Kirk: That's the way it was in 1881.
Spock: I wonder how humanity managed to survive.
Kirk: We overcame our instinct for violence.
There are several historical goofs in this episode. Wyatt Earp, despite the sign in this episode, was not the Marshal of Tombstone. His older brother Virgil was. Wyatt and Morgan were Deputy Marshals. Also, in reality, the actual gunfight took place outside Fly's Photographic Studio, a good distance from the O.K. Corral. Nor did the gunfight occur at 5 p.m. These inaccuracies have an excuse here because they come from Kirk's romanticized conceptions of the Old West, or alternately because he doesn't remember it very well.
When the Earps march toward the gunfight, they pick up Holliday and he's on the (stage) left end of the formation. In the next shot, he's second from the left. When the group arrives at the O.K. Corral, Holliday has moved entirely to the right side of the line.
In the closing scene of the remastered episode, there's an odd sound reverb over Spock's line "I wonder how humanity managed to survive."