Kingdom Hearts 3D: Dream Drop Distance
Kingdom Hearts 3D: Dream Drop Distance
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.
Contributed by ABOhiccups
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.
Contributed by gamemaster1991
The character Julius (from the Mickey Mouse short Runaway Brain) is a secret boss in the game. The player must beat the story of the game, and return to Traverse town in order to fight him.
Contributed by CLXcool
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.
Contributed by CuriousUserX90
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.
Contributed by Psychospacecow
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
Contributed by Chazyx
Kingdom Hearts 3D: Dream Drop Distance is the first game in the series that doesn't include Olympus Coliseum.
Contributed by gamemaster1991