This is the first game in the Kingdom Hearts series to feature a world based on one of Disney's direct-to-video films. Specifically, Country of the Musketeers is based on the 2004 direct-to-video film "Mickey, Donald, Goofy: The Three Musketeers".

There are hidden rooms in the game's code. Some of the hidden rooms are part of cutscenes, while the rest are designed for boss fights. The only way to access hidden rooms is to hack the game's save files.

Two unused maps can still be found in the game's data. One is a pirate ship and the other is a round room with four doors.

After beating the game's main story, returning to Traverse Town will allow you to fight a secret boss. This boss character is Julius, from the 1995 Mickey Mouse short "Runaway Brain".

You can find a graffiti picture in Traverse Town which bares a resemblance to the logo for CAT, a company in the video game The World Ends with You.

Pre-release footage of the game shows Sora fighting Heartlesss and Nobodies, which were replaced by Dream Eaters in the release version.

Several hints towards Kingdom Hearts III can be found in the credits for the game. Flying through all of the golden letters during the credits will unlock a secret message, stating "The past will be reawakened as a new number in never-before-seen detail. Prepare yourself for the awakening of the next number."

Additionally, several letters appear in the credits. When typed out in order of appearance, the letters spell out "this leads to KINGDOM HEARTS". Riku and Sora will then be shown walking into the light, making 3 pillars of light.

This is the first game in the series that grants a magic command that goes to the fourth level of magic thus ending in "iza". The spell is gravity class and named Zero Graviza.

Kingdom Hearts 3D: Dream Drop Distance is the first game in the series that doesn't include Olympus Coliseum either as a world or an appearance in a flashback. However, one of its recurring themes "Road to a Hero" is used during Country of the Musketeers.

Some unused 3D models and an image of the demo of Kingdom Hearts 3DS: Dream Drop Distance's logo can be found in the Japan-only Final Mix re-release of Kingdom Hearts: Birth by Sleep, suggesting that Dream Drop Distance uses a modified Birth By Sleep graphical engine.