Trivia: The Daystrom Institute and Dr Richard Daystrom himself would be referred to many times during the course of the follow-up Star Trek series Next Generation, DS9, and Voyager.
Bones says "Jim he's on the edge of a nervous breakdown, if not insanity!". Given that statement by the ship's doctor, one would think it's probably not a good idea to upset Dr. Daystrom any more than he already is. But what does Kirk do? He immediately charges up to Dr. Daystom and says the worst thing you could possibly say to him at that point--"The M-5 must be destroyed!".
When the M-5 computer goes crazy and starts shooting at the other starships, Commodore Wesley instantly concludes that Capt. Kirk has lost his mind and is trying to kill everyone. Not even for one second does the Commodore think that the M-5, which is going through its trial test and which has complete control of the ship, is the cause of the problem. It also doesn't reflect well on their friendship that his first and immediate conclusion is that Kirk is nuts.
When McCoy, Kirk and Spock come out of the turbolift, McCoy's lips don't move saying "Very funny."
McCoy disappears then reappears throughout the scene when Spock and Scotty are trying to disable the M-5.
After McCoy sedates Daystrom, the three of them walk out through the sickbay doors and down the hall while the camera stands still in sickbay. Yet the doors don't close.
In one scene on the bridge of the U.S.S. Lexington, the space sensor array wasn't moving.
McCoy: Why don't I get the man who is responsible in the first place? Where's Daystrom?
Kirk: He's with the M-5 unit... watching it. I think it surprised even him.
Spock: Most illogical. Of all people, he should have known how the computer would perform. Of course, the M-5 itself has not behaved... logically.
McCoy: Please, Spock, do me a favor and don't say it's fascinating.
Spock: No. But it is.... interesting.
McCoy: Did you see the love light in Spock's eyes? The right computer finally came along.
Kirk: ...I stood on the bridge of my ship and I felt useless! (He raises his glass in a toast.) To Captain Dunsel.
McCoy: To James T. Kirk, Captain of the Enterprise.
McCoy: Compassion. That's the one thing no machine ever had. Maybe it's the one thing that keeps men ahead of them. Care to debate that, Spock?
Spock: No, Doctor. I simply maintain that computers are more efficient than human beings, not better.
McCoy: But tell me, which do you prefer to have around?
Spock: I presume your question is meant to offer me a choice between machines and human beings. And I believe I have already answered that question.
McCoy: I was just trying to make conversation, Spock.
Spock: It would be most interesting to impress your memory engrams on a computer, Doctor. The resulting torrential flood of illogic would be most entertaining.
McCoy: I don't like it, Jim. A vessel this size cannot be run by one computer.
Spock: We are attempting to prove that it can run this ship more efficiently than man.
McCoy: Maybe you're trying to prove that Spock, but don't count me in on it.
Spock: The most unfortunate lack in current computer programming is that there is nothing available to immediately replace the starship surgeon.
McCoy: Very funny.
Kirk: There are certain things men must do to remain men.
Kirk: Only a fool would stand in the way of progress.
Spock: Computers make excellent and efficient servants, but I have no wish to serve under them. Captain, a starship also runs on loyalty to one man. And nothing can replace it or him.
Kirk: Genius doesn't work on an assembly line basis. You can't simply say, "Today I will be brilliant."
McCoy: If a man had a child who'd gone anti-social, killed perhaps, he'd still tend to protect that child.
Kirk: What happened to the crewman?
Richard Daystrom: The M-5 computer needed a new power source; the crewman merely got in the way.
Kirk: And how long will it be before we all "just get in the way?"
Richard Daystrom: When a child is taught ... it's programmed with simple instructions -- and at some point, if its mind develops properly, it exceeds the sum of what it was taught, thinks independently.
Richard Daystrom: To kill is a breaking of civil and moral laws we've lived by for thousands of years.
M-5: Murder is contrary to the laws of man and God.
McCoy: We're all sorry for the other guy when he loses his job to a machine. But when it comes to your job -- that's different. And it always will be different.
Kirk: Do you know the one -- "All I ask is a tall ship...and a star to steer her by..." You could feel the wind at your back, about you... the sounds of the sea beneath you. And even if you take away the wind and the water, it's still the same. The ship is yours...you can feel her...and the stars are still there.
Commodore Robert Wesley: Our complements to the M-5 unit ... and regards to Captain Dunsel. Wesley out.
(Chekov winces; he and Sulu exchange a look)
Dr. McCoy: Dunsel? Who the blazes is Captain Dunsel? What does it mean, Jim? ... Spock? ... What does it mean?
Spock: Dunsel, doctor, is a term used by midshipmen at Starfleet Academy. It refers to a part which serves no useful purpose.
Richard Daystrom: Destroy it, Kirk? No! We're invincible! Look what we've done! Your mighty starships ... four toys to be crushed as we choose!
Richard Daystrom: (growing increasingly agitated) Twenty years of groping to prove the things I'd done before were not accidents. Seminars and lectures to rows of fools who couldn't begin to understand my systems. Colleagues ... colleagues laughing behind my back at the boy wonder... then becoming famous building on my work... building on my work!
The ore freighter model shown in this episode is recycled from Khan's deep-sleep ship from "Space Seed." The explosion shown is also recycled, shown earlier in "The Changeling." In the remastered 2008 version, both are redone from scratch.
The picture of the four ships attacking the Enterprise is actually one picture of the Enterprise quadrupled. In the 2008 remastered edition this was changed so that each ship was the same style, but had different names and numbering. The visuals for the approach of the ships and the attacks in the 2008 remaster were similar to the visuals done for the XBox/Playstation 2 game Star Trek Shattered Universe during the M-5 mission.
The badly damaged model of the Excalibur was the same model used for the Constellation in "The Doomsday Machine".
The Lexington bridge is in fact a slightly altered version of the Enterprise bridge. An extra seat back was added which was originally used in "Mirror, Mirror."
Deep Space Station K-7 is seen in this episode. As seen here, it is recycled footage from "The Trouble with Tribbles." In the remastered version, a new CGI model is used, complete with the Lexington docked with it.
The name Robert Wesley is Gene Roddenberry's alias.
The U.S.S. Potemkin (NCC-1657) will be given mention in the series finale, "Turnabout Intruder."
Desilu No: 5149-53.