David Gerrold and Oliver Crawford submitted the original script, "Castle in the Sky." It was substantially rewritten by Margaret Armen at the producers' request, with a happier ending added. Gerrold disavowed the script, although his name still appears. Another working title was "Revolt."

Jeff Corey (Plasus) was Leonard Nimoy's acting coach in the late 1940s. They remained close friends until Corey's death in 2002.

For the first and only time in the series, Spock has an internal thought monologue as he considers the situation on Ardana.

Droxine: I have never before met a Vulcan, sir.
Spock: Nor I a work of art, madam.

Prisoner: I came to make repairs.
Plasus: And you shall make them by giving us the names of the Disrupters.
Prisoner: I know nothing.
Plasus: I would advise you to increase your knowledge.
Prisoner: That is not possible for a Troglyte. The Stratos city dwellers have said it.

Spock: This troubled planet is a place of the most violent contrasts. Those who receive the rewards are totally separated from those who shoulder the burdens. It is not a wise leadership. Here on Stratos, everything is incomparably beautiful and pleasant, the high advisor's charming daughter Droxine particularly so. The name Droxine seems appropriate for her. I wonder... can she retain such purity and sweetness of mind and be aware of the life of the people on the surface of the planet? There, the harsh life in the mines is instilling the people with a bitter hatred. The young girl who led the attack against us when we beamed down was filled with the violence of desperation. If the lovely Droxine knew of the young miner's misery, I wonder how the knowledge would affect her.

Droxine: I did not realize they would disturb you.
Spock: Only Vulcan ears would find the noise discernible.
Droxine: It seems that Vulcan’s are fascinatingly different in many ways.
Spock: The same may be said of Stratos inhabitants.
Droxine: Vulcan eyes are very discerning too. I hear that intellectually, Vulcan’s are as highly evolved as Stratos city dwellers.
Spock: We do pride ourselves on our logic.

Vanna: You sleep lightly, Captain.
Kirk: Yes, duty is a good teacher. I see you've changed your dressmaker.

Vanna: Call the guards if you’re afraid, Captain.
Kirk: I'm not afraid. (holding her on the bed) In fact, I find this rather enjoyable.
Vanna: I do not!

Droxine: You only take a mate once every seven years?
Spock: The seven-year cycle is biologically inherent in all Vulcans. At that time, the mating drive outweighs all other motivations.
Droxine: And is there nothing that can disturb that cycle, Mr. Spock?
Spock: Extreme feminine beauty... is always disturbing, madam.

Droxine: The Troglytes are workers, Captain. Oh, surely, you must be aware of that. They mine zenite for shipment, till the soil. Those things cannot be done here.
Spock: In other words they perform all of the physical toil necessary to maintain Stratos.
Droxine: That is their function in our society.
Spock: But they are not allowed to share its advantages.
Droxine: How can they share what they do not understand?
Kirk: They can be taught to understand. Especially in a society that prides itself in enlightenment.

Spock: Violence in reality is quite different from theory, is it not, madam?
Droxine: But what else can they understand, Mr. Spock?
Spock: All the little things you and I understand and expect from life, such as equality, kindness, justice.

Vanna: Centuries ago, Stratos was built by leaders that gave their word that all inhabitants would live there. The Troglytes are still waiting.
Kirk: The zenite can be delivered in a few hours. You won't have long to wait now.
Vanna: Hours can be centuries, Just as words can be lies.

Vanna: We're sealed in!
Kirk: Completely.
Vanna: But soon the atmosphere will go. We'll die!
Kirk: Die from something that can't be seen? You astound me, Vanna.

Scotty: Beam the high advisor down without warning, did he say?
Spock: That's not an exact quote, Mr. Scott. However, it does express the thought.
Scotty: I'd like to see the advisor's face.
Spock: You'll have that opportunity.
Scotty: The captain did say immediately, did he not?
Spock: Now, that is an exact quote, Mr. Scott. And I suggest you handle the transporter yourself. This could be very delicate as a problem in transporting for us... and in diplomacy for the captain.
Scotty: Aye.

Droxine: No, I wasn't thinking of Captain Kirk. It's the one with those exquisitely shaped ears. His name is Spock. He's the one I was thinking about. Did you know that he has the most incredibly sensitive hearing? Why, I almost believe that if I stood here and called out to him, he would hear my invitation to come and visit with us for a little while longer.

Kirk: The Troglytes will no longer suffer from retardation and emotional difficulties.
Plasus: They will all be like her: ungrateful, vindictive!
Vanna: Yes, our demands have just begun.

Kirk's mouth doesn't move as he is captured by the Troglytes and says "Who are you? What is the meaning of this attack?" Some syndicated versions have cut the line, and the remastered version uses a different shot of the back of Kirk's head as the line is spoken, eliminating the goof.

The pon farr cycle is revealed here as lasting seven years.

What Changed in the Remastered Version
General improvements cited on the main series page. The orbital shots of Ardana get a surface upgrade. The cloud city of Stratos receives a significant FX upgrade, receiving a more alien architecture. A more detailed skyline, including moving clouds, can be seen behind it. The planet view, originally taken from an orbital photo of the Hadramawt Plateau in Saudi Arabia, is reused and incorporated here, significantly touched up. The energy effect used in Vanna's torture sequence is enhanced. The falling Troglyte prisoner sequence is shown digitally.


Original vs. Remastered


Original vs. Remastered