Trivia: For once, Kirk is wearing a black undershirt as well as his tunic. When he falls off the chair you can see a shirt instead of a bare chest. This is unusual for Kirk. Most often his uniform doesn't include the undershirt as you can tell in other episodes where it is torn.
The two transporter operators at the beginning are unusually unprofessional. Neither one of them knows that penal colonies have security screens, or even understand that a security screen is blocking their transporter beam.
When the intruder alert goes off, a security guard come to the bridge. This makes sense. What doesn't make sense is that once he makes sure there's no intruder on the bridge, he faces away from the turbolift: the only entrance onto the bridge that an intruder could come through. Sure enough, Van Gelder comes in behind him and knocks him out before he can respond. The guard fails to respond despite the fact that he should be at attention.
The transporter operator (Berkley) is credited as an ensign, but the uniform is clearly that of a Lieutenant.
When Kirk escapes the Tantalus field, he knocks out Dr. Adams and punches out another person before leaving. When he comes back only a few moments later, only Dr. Adams is on the floor.
Tantalus V has really lousy security. In addition to Van Gelder escaping in a box, Dr. Noel is able to easily access the ventilation system from Kirk's quarters and just waltz into the power control room and shut down the power for the entire colony, including the force field.
Since Kirk is down on Tantalus to investigate the incident involving Dr. Van Gelder, it seems that it would make more sense for Dr. Adams to not try to brainwash Kirk and, instead, try to get Kirk out of there as quickly as possible by appeasing him in every way possible.
Considering the known consequences of unsupervised exposure to the beam, one might expect the device to be equipped with a deadman switch: it can't operate without an individual at the controls, as it does. There is no reason for Dr. Adams to have disengaged or left out such a device.
The neural neutralizer is likely an enormously complex device -- and yet, it has only one switch, a combination on/off and power level setting. It seems highly likely that such a device would require either a programming input, or a series of configuration switches. Even now, we know that brain activity and structure differs between individuals.
It looks like the wardrobe department gave Marianna Hill (Dr. Helen Noel) a Starfleet mini-dress uniform that is way too short for her. The skirts are supposed to be short, but Helen's skirt is so short in the back that it does not even completely cover her matching bloomers.
The space sensor array wasn't spinning at the beginning of this episode.
In the transporter room at the beginning, they contacted Tantalus V even though they had their shields up, when Kirk beams down, he attempts to use his communicator but he gets static, the shield is turned off and he can communicate with the Enterprise, later when the shield is up, he gets through just fine.
Adams' plan doesn't seem to make much sense - he cranks up the neural neutralizer to supposedly convince Kirk that it works. In previous cases it's turned people into zombies. Alternately, if Adams plans to use Kirk in some manner, it doesn't seem like a zombified Kirk is going to be very effective in helping him take the Enterprise.
For a penal colony, Tantalus V has really poor security. Van Gelder manages to escape with ease, by hiding in a box - the only box - beamed up to the Enterprise.
Dr. Adams: Captain, you remind me of the ancient skeptic who demanded of the wise old sage to be taught all the world's wisdom while standing on one foot.
McCoy: It's hard to believe that a man could die of loneliness.
Kirk: Not when you've sat in that room.
Kirk: But (Adams) was alone. Can you imagine the mind emptied by that thing, without even a tormentor for company.
Spock: Interesting. You Earth people glorify organized violence for forty centuries, but you imprison those who employ it privately.
McCoy: And, of course, your people found an answer.
Spock: We disposed of emotion, Doctor. Where there's no emotion, there's no motive for violence.
Kirk: One of the advantages of being a captain is being able to ask for advice without necessarily having to take it.
Features recycled Delta Vega matte painting from "Where No Man Has Gone Before," this time for Tantalus colony, with refinery tanks removed and entrance doorway changed.
This episode is parodied by South Park in Episode 24 (Production code 211) "Roger Ebert Should Lay Off the Fatty Foods." That episode is littered with references, including a mindmeld between a counselor and a student.
First mention and use of the Vulcan mind-meld. In Star Trek: Enterprise episode, "The Forge", Syrrann, the Vulcan who discovered Surak's katra, said "Surak tells us... (mind-melding) is the heritage of every Vulcan."
This is the second (and last time) that a holiday celebration is mentioned - "Charlie X" mentions Thanksgiving. One wonders if they celebrate a secular version of Christmas?
Writer Shimon Wincelberg is credited as S. Bar-David.
A Greek myth about a man who commits crimes and is punished by the gods by never being able to satisfy his thirst or hunger. The stream of water would recede when he reached for it, the fruit trees' branches would raise when he reached for fruit.
The patient who has had her memories removed is named Lethe, after a river in the classical Greek underworld that appears in Dante's Inferno. The river Lethe had a unique property that whoever drank of it would lose all memory of their previous life.
Referencing Shakespeare's MacBeth:
"Is this a dagger which I see before me, / The handle toward my hand? Come, let me clutch thee. / I have thee not, and yet I see thee still. / Art thou not, fatal vision, sensible / To feeling as to sight? or art thou but / A dagger of the mind, a false creation..."
In plotting a murder to gain the throne, Macbeth causes himself considerable mental anguish, seeing an unreal dagger that is really a symbol of his guilt.