There's a lot of stuff going on in this episode. Angela Martine, who we last saw mourning the death of her fiancé in the previous episode, "Balance of Terror", also appears in this episode, exchanging flirtatious dialogue with one Lieutenant Esteban Rodriguez. Apparently she got over her fiancé's death pretty quickly. In secondary scenes, the two of them encounter a tiger, and then get strafed by a Japanese Zero fighter. I wanted to include a panel of Esteban shouting, "Ze plane! Ze plane!", but I couldn't squeeze it in.
Also, they state several times that their sensors showed no animal life or technology or power sources or even refined metals anywhere on the planet. Yet we learn later on that there's an entire industry of robotic factories underground, churning out these fantasy items at the whim of the guests. They had a similar problem back in Captain Pike's day, as shown in "The Menagerie", when scans showed no technology at all on Talos IV, despite the presence of an entire civilisation hidden just below the surface. Perhaps Starfleet should invest in some ground-penetrating radar tech.
Captain's log, Stardate 3025.3. Scouting an uninhabited planet for suitability for extended shore leave.
Sulu: Scans show no animal life or technology.
McCoy: It's like Wonderland.
White Rabbit: Oh my whiskers, I'm late!
McCoy: Um... er...
White Rabbit: Nyah, what's up, Doc?
Kirk: You met a giant rabbit?
McCoy: I think so...
Yeoman Barrows: I wish I could meet a real man.
Yeoman Barrows: Eeek! A man came up and ripped my uniform!
McCoy: Sounds like Don Juan. Or possibly the captain. I'll protect you!
Yeoman Barrows: My knight in shining armour! I feel like a princess.
Yeoman Barrows: Funny finding this princess dress.
McCoy: That black knight about to attack is even funnier. But it can't be real. It can't hurt me.
McCoy: Or maybe it can...
Spock: He's dead, Jim.
Kirk: It's like some big practical joke, played by my old rival from the Academy.
Finnegan: Hey, Jimmy boy!
Kirk: Finnegan! Remember when you speared our instructor?
SFX: Punch! Punch!
Spock: Enjoy yourself, captain?
Kirk: Immensely. A fist fight in which I ripped my shirt more than ever before!
Spock: I believe this planet somehow makes our fantasies into reality.
Kirk: Yes... Like this rock formation... I've seen it before.
Kirk: Who are you?
Caretaker: My dear guests! I am the Caretaker, your host. Welcome... to Fantasy Planet.
McCoy: I'm not really dead!
Yeoman Barrows: You will be if you don't drop those ladies, pronto.
McCoy: But... fantasies!