The Game
- Celebrity Voice Actor: Ansem the Wise's voice was provided by Christopher Lee.
- Colbert Bump: TRON got a lot of exposure due to the inclusion of a world based on it, which in turn helped it get a sequel in TRON: Legacy 5 years after Kingdom Hearts II's release, which itself would get a world in Kingdom Hearts 3D [Dream Drop Distance].
- Creator's Favorite: Nomura stated in a 2014 interview
that the Pride Lands is his favorite world. - Dummied Out:
- Models for a scrapped Woody & Buzz summon can be found in the files of the Final Mix version.
- The Edge of Ultima and Detection Saber, two palette-swapped versions of the Ultima Weapon, are found in the game files and can be accessed using cheat codes. Their effects are the same as Oblivion. Donald and Goofy also have similar weapons called Staff of Detection and Detection Shield respectively. They were most likely used as collision models in the game's test phase.
- The E3 2005 and the TGS 2003 trailers show scenes that were ultimately removed from the final release of the game.
- The old Munny sprite was used in earlier trailers, but was removed in favor of a new sprite.
- The No Experience ability is present in the original, non-Final Mix version. It's fully functional, but there's no way to obtain it without hacking.
- The Behemoth from the first game was going to appear in Hollow Bastion, but got cut due to causing the game to lag.
- Executive Meddling: Tetsuya Nomura had originally planned to only include Final Fantasy characters that he personally designed, as he is more familiar with them. The staff urged him to include other characters and he caved, which is how Setzer from Final Fantasy VI and Vivi from Final Fantasy IX were added to the game.
- Fandom Nod: In addition to all the Disney/Final Fantasy references, there is a literal fandom nod during Cloud and Leon's snark-fest in the sequel. As they do their Back-to-Back Badasses moment, it echoes the rivalry between fans of their respective games.
- Keep Circulating the Tapes: Kingdom Hearts II remains as the only game of the franchise with a Spanish dub in a similar case that of Metal Gear Solid. However, the 2.5 compilation release did not include it and the dub only remains in the PlayStation 2 game copies. It's highly unlikely that the dub will ever be available again in any following re-releases as other titles of the franchise did not receive one plus the fact that the 2.5 Final Mix includes new scenes. Though YouTube users have edited compilation videos of the games' remastered HD scenes with the PS2 game's dub.
- Limited Special Collector's Ultimate Edition: The Final Mix version includes a ton of extra content compared to vanilla Kingdom Hearts II, and it is topped by Final Mix+, which packs in a remake of Kingdom Hearts: Chain of Memories. While the latter eventually was eventually given a standalone release in North America, Final Mix wasn't released outside of Japan until the Kingdom Hearts HD II.5 HD ReMIX compilation.
- Meme Acknowledgment: A popular meme-based Fan Nickname for Xemnas is "Mansex". His English voice actor, Paul St. Peter, has actually called him that.
- Missing Trailer Scene:
- Donald freezing himself with a ricocheting Blizzard after waking up from his memory-restoring sleep.
- The TV spot released in North America featured Sora fighting Axel, which wasn't present in the original game.
- Roxas chases the Dusk thief through the streets of Twilight Town, and it escapes by flying into a wall and vanishing.
- Axel walks closer to the far wall in the scene before his fight with Roxas; as he approaches it, he looks back at Roxas and grins a Slasher Smile.
- The Kingdom Hearts I version of Hollow Bastion, specifically the Great Crest, appears as the place where Sora first met the surviving members of the Organization, after the trio slays a horde of Neoshadows.
- Sora meets King Mickey in his Kingdom Hearts II attire before visiting the Mysterious Tower.
- Sora was shown on the Dark Margin and holding his Keyblade up to something like he was getting ready to seal a keyhole.
- One-Take Wonder: Reportedly, Christopher Lee insisted on only doing a single read-through for his lines and then walking out of the studio due to his busy schedule. As the voice director noted (and fans tend to agree), the single takes were all Lee needed to do anyway since he nailed the delivery every time.
- The Original Darrin:
- In the first Kingdom Hearts game, Hercules was played by Sean Astin, and the Mayor of Halloween Town by Jeff Bennett. Here in II, Astin and Bennett are replaced by Tate Donovan and Glenn Shadix, the original actors from Hercules and The Nightmare Before Christmas.
- The Little Mermaid (1989) cast member Christopher Daniel Barnes returns to the role of Prince Eric for the first time ever, having been replaced by Jeff Bennett in the TV series and Rob Paulsen in the sequel.
- The Other Darrin:
- Richard Epcar replaces Billy Zane as Ansem, Seeker of Darkness.
- Mae Whitman replaces Christy Carlson Romano as Yuffie, Doug Erholtz replaces David Boreanaz as Leon, and Mena Suvari replaces Mandy Moore as Aerith.
- George Newbern replaces Lance Bass as Sephiroth.
- Meaghan Jette Martin replaces Brittany Snow as Naminé in the II.5 Final ReMIX version, but only for the new and expanded scenes that weren't in the original PS2 version. Brittany Snow's lines are otherwise intact.
- Several Disney characters were given this treatment from their source material, at least one in every world. Agrabah (Genie), Beast's Castle (Lumiere),note The Land of Dragons (Mushu), and Olympus Coliseum (Phil) are all missing only one of their original voice actors each, though all are replaced by their official other Darrins. Simba, Shenzi, Nala, Scar and Timon from Pride Lands do not have their original actors back, nor do Flounder and Sebastian in Atlantica, the MCP and Sark for Space Paranoids, or anyone at all in Port Royal, 100 Acre Wood, and Timeless River. However, most of them are replaced by their official other Darrins, meaning those voices are reprised. Simba and Mushu are mixed cases- their voice actors in KH provided the singing voices in the movies for their characters (apparently, in Mushu's case). Of note is that this game marks the debut of Travis Oates as the official voice actor for Piglet, replacing the late John Fiedler, who voiced him in the first game and was his original voice actor since his first animated appearance in 1968.
- Role Reprise:
- Angela Lansbury, David Ogden Stiers, Robby Benson, and Paige O'Hara voice Mrs. Potts, Cogsworth, the Beast, and Belle again.
- Bruce Boxleitner reprises his role as Tron.
- Tate Donovan, the original voice actor for Hercules, reprises his role after not coming back for Kingdom Hearts. Susan Egan also returns as Megara.
- Ming-Na Wen, BD Wong, Harvey Fierstein, Gedde Watanabe, Jerry Tondo, and Pat Morita reprise their roles as Mulan, Shang, Yao, Ling, Chien-Po, and The Emperor in the Land of Dragons; it was the last voice role for Morita, as he had died a few months before the game released.
- Robert Guillaume, Ernie Sabella, Cheech Marin, and Jim Cummings return as Rafiki, Pumbaa, Banzai, and Ed respectively. Archive recordings of James Earl Jones are used for the revisited scenes from the original film with Mufasa.
- Jodi Benson, Pat Carroll, Christopher Daniel Barnes, and Kenneth Mars return as Ariel, Ursula, Eric, and King Triton, respectively. This also ended up being the last time Mars voiced Triton in any media before his illness and later death.
- On the Final Fantasy side, Hideo Ishikawa and Matt McKenzie reprise their roles as Auron from Final Fantasy X in Japanese and English, respectively.
- So My Kids Can Watch: Part of Boxleitner's reason for the Role Reprise. His youngest son was playing through the game and got to the Space Paranoids level…"That's you, Dad? You were cool!"
- Two Voices, One Character: In the HD 2.5 ReMIX version, Meaghan Martin voiced Naminé for the character's extra lines from Final Mix, while Brittany Snow's performance from the base game is kept.
- Uncredited Role: The ending credits for the 2.5 HD Remix version are not updated to include Meaghan Jette Martin for her brief return as Naminé in the Final Mix-exclusive scenes.
- What Could Have Been:
- Word of God states that this game was originally supposed to be the second game of the series, instead of Chain of Memories, which was eventually developed in an attempt to bridge the gap between I's Cliffhanger ending and II's mysterious opening.
- Axel was originally supposed to die at the end of the prologue. The development staff liked him too much to remove him from the story that early, so his role was expanded.
- Buzz and Woody from Toy Story were going to be a Summon in the Final Mix version, but were scrapped. Their unfinished models are still in the game files. Eventually, a Toy Story based world was confirmed for Kingdom Hearts III.
- Early trailers suggest that the outside walls of Hollow Bastion's castle from the first game would be playable.
- Variations on the Behemoth and Wyvern Heartless were present in the Battle of 1000 Heartless in older trailers.
- Xemnas was going to have two different forms for the final battle, the "King" and "Centaur"◊. They would have him apparently breaking up and surrounding himself with chunks of the Dark City to create something akin to the giant dragon that is fought in the final game.
- The game was planned to feature battles against all of the Organization members in the Coliseum, but they had to be dropped due to lack of time. This was re-imagined into the Data battles found at the end of the Cavern of Remembrance in the Final Mix version.
- Some concept art shows that double-bladed Keyblades◊ were considered at one point.
- David Warner wanted to reprise his roles as the MCP and Sark, but he was not able due to pre-existing commitments at the time.
- There is an unused version of the Final Fantasy IX world map theme in the game's coding. There are a few theories for it: some think it was going to be used for the fight with Vivi, and others think that Vivi (or even other characters from FFIX) was going to play a larger part in the story.
- If the E3 2005 trailer is any indication, the game was originally going to feature a camera angle similar to the one from Kingdom Hearts I; that is, to say, it was going to be zoomed in a lot closer to Sora during the action.
- Setzer's cameo was originally filled by Rufus Shrina from Final Fantasy VII. Nomura realized that the Final Fantasy representation already skewed pretty heavily towards VII, so he told scenario writer Kazushige Nojima to use Setzer specifically because he was from Final Fantasy VI. Unfortunately, the lack of significant alteration to the part resulted in many finding Setzer wildly out-of-character.
- Tifa wasn't planned to appear initially, even though Cloud and Sephiroth were. The team later realized that she fit in with Cloud's narrative as the thing he was running from.
The Manga
- Keep Circulating the Tapes: Tokyopop's old translation of the first two volumes are this, especially after Yen Press made a whole new translation.
- Screwed by the Network: Tokyopop's original English release was this after only two volumes, thanks in part to a restructuring of the company. When Tokyopop went under for a few years, it was uncertain on whether the manga would continue in the states. Fortunately, Yen Press came to the rescue.
- Series Hiatus: After Volume 5 came out, the manga was put on hold while Shiro Amano worked on the adaptation of Kingdom Hearts: 358/2 Days.
