The end credits feature a still of a white-skinned bald android in a brown jumpsuit. This is an unused footage of a scene from "Return From Tomorrow" featuring one of the created androids.

Spock: (Humans) find it easier to understand the death of one than the death of a million. You speak about the objective hardness of the Vulcan heart. Yet how little room there seems to be in yours.
McCoy: Suffer the death of thy neighbor, eh, Spock? Now you wouldn't wish that on us, would you?
Spock: It might have rendered your history a bit less bloody.

Kirk: Insufficient data is not sufficient, Mr. Spock. You’re the science officer, you’re supposed to have sufficient data all the time.

Kirk: Recommendations?’
McCoy: I have one. I recommend survival. Let’s get out of here.

Spock: Captain, the Intrepid would've done all these things, too, and yet, they were destroyed.
Kirk: Well, they may not have done all these things. You've just pointed out how illogical this situation is.
Spock: True. It is also true they never knew what was killing them. Their logic would not have permitted them to believe they were being killed.
Kirk: Explain.
Spock: Vulcan has not been conquered within its collective memory. The memory goes back so far that no Vulcan can conceive of a conqueror. I knew the ship was lost because I sensed it.
Kirk: What did you sense?
Spock: A touch of death.
Kirk: And what do you think they felt?
Spock: Astonishment.

Spock: This is not a competition, Doctor. Whether you understand it or not, grant me my own kind of dignity.
McCoy: Vulcan dignity? How can I grant you what I don’t understand?
Spock: Then employ one of your own superstitions. Wish me luck.

Spock: Tell Dr. McCoy… he should have wished me luck.

Spock: I have noted the passage of the Enterprise on its way to whatever awaits it. If this record should survive me, I wish it known that I bequeath my highest commendation and testimonial to the captain, officers, and crew of the Enterprise… the finest starship in the fleet.

McCoy: Shut up, Spock, we're rescuing you!
Spock: Why, thank you, Captain McCoy.

Kirk: Spock, you're alive!
Spock: Obviously, Captain. And I have some fascinating data on the organism.
McCoy: Don't be so smart, Spock. You botched the acetylcholine test.

Kirk keeps referring to Lt. Kyle as "Lt. Kowl."

McCoy wears his short-sleeved uniform throughout the episode, but when he opens the shuttle bay door, the insert shows a long sleeve.

Lt. Kyle is on the bridge in a yellow uniform, although typically he is in a red uniform and mans the transporter. He wears the yellow uniform so that he'll match when they used recycled footage of Chekov's shoulder.

The Intrepid is the second of four Constellation-class starships that are destroyed during the course of the original series.

What Changed in the Remastered Version: The large "space amoeba" (or whatever it was) received some nice upgrades; in the original series it was clearly a preserved specimen (accounting for its bright colors). Here, the colors were preserved (for continuity reasons - there is no particular reason such a creature would evolve to emit light, wasting energy) but the organism was animated to somewhat resemble the observed behavior of living unicellular organisms. Several nice (if brief) scenes depicted the Enterprise flying through the inner structure of the organism as it attempted to approach the nucleus. Small bits of internal matter (or parts of the Intrepid?) can be seen drifting by the ship.