Like a quodlibet of TOS's favorite ideas, "The Apple" includes a false paradise, childlike aliens, speeches about freedom, and a machine for Kirk to overthrow... not to mention ridiculous make-up, costumes and wigs.
Most of the episode takes place on the "alien planet" stage set with the same red cyclorama sky used in "Amok Time". It's basically another version of "Who Mourns for Adonais", with the plot moving in circles while Kirk tries to figure out how to save himself and his ship. But whereas "Adonais" has a noble quality and Michael Forrest brings a presence to Apollo, this one is sillier, and Kirk's opponent is a serpent head that looks like a papier-mch project gone wrong. (Although to be fair, the creature is really made of aluminum foil). To make matters worse, the thing's spokesman is Akuta, terribly played the wooden Keith Andes. Why would anyone cast Andes, nearing the age of 50 at the time of the shoot, as a childlike youngster who likes to run around mostly naked?
Still, the episode has some interesting ideas, from McCoy and Spock's continuing debate over the Prime Directive to the first talk of a saucer separation. And Walter Koenig shines, with the writers finally figuring out how to use Chekov. (There's also a young David Soul, who would go on to be the latter half of "Starsky & Hutch", playing Makora, a young alien experimenting with For Mr. Spock, the redshirts, and the rest of us, however, it's a rough day at the office.
Remastered Version: With not much to do and no reason to do much, "The Apple" gets the basic makeover with new CGI shots of the planet and the ship. Because of stage set's red sky, the original episode reuses Vulcan from "Amok Time" (the planet in the opening credits). The new version, however, goes for a more Earth-like planet, which is a curious choice. Moreover, whereas the original uses some stock footage of clouds and tints them red, the remastered counterpart filters out the red, creating a new look that doesn't match the sky of the stage set. To make matters worse, in the second season Blu-ray set which supposedly gives viewers the choice of watching this episode in the original or remastered way, the new, de-tinted version of the stock footage appears in both versions, with CBS Digital apparently forgetting they made a change and not accounting for it.