There is an unused version of the sound of Pepper pulling out his skateboard, which is followed by an excerpt from Apocalypse Now: "I love the smell of napalm in the morning!"
This was most likely put in by mistake by the developers.

There is an unused musical track in the game's files by the name of "Town Bridge". It is unknown what this track would have been used for, as there isn't a bridge, besides a small road bridge, in the game.

There is an inaccessible area on Adventurers' Island, near the pyramid. It can be seen by clipping the camera through the wall of sand next to the pyramid. It only contains a short, curved hallway, four pillars, and a coffin. Instead of removing it, the developers just blocked off the entrance.

In the PC version of the game, after obtaining 100% completion, it's possible to open a portal on the side of Space Mountain where a cave can be seen. To open the portal, the player must type in the code "sdreams". Inside the portal are LEGO Minifigure versions of most of the development team that worked on the game at Silicon Dreams.