Within the code for the game's December 29, 2003 demo is a placeholder pause screen with an uncharacteristically violent illustration of Kirby bleeding to death. Curiously, the text on the illustration appears to reference theological concepts most notoriously promoted by the Japanese doomsday cult and terrorist group Aleph (formerly known as Aum Shinrikyo). The placeholder screen is designed for a "WAIT" state carried over from Kirby: Nightmare in Dream Land, wherein it is used when a player dies in the game's multiplayer mode. No such state is used in either the demo or the final game.

To keep with the trend of Kirby looking angry on the North American box art, the faces of the red and pink Kirbys were switched, giving the pink Kirby the red Kirby's scowl.

Master Hand and Crazy Hand from the Super Smash Bros. series both make an appearance in this game as one of the main bosses, with Master Hand also appearing as a mini-boss throughout the overworld. Both attack similarly to their Super Smash Bros. counterparts.

Defeating the Master Hand mini-boss also allows the player to inhale Master Hand, giving the player the "Smash" ability, where Kirby can use all of his Super Smash Bros. moves.

The Missile ability deals different amounts of damage in the Japanese and English versions. It deals 6 (direct hit) and 2 (explosion) in the Japanese version, and 4 (direct hit) and 1 (explosion) in the English version.

In the Japanese release, a glitch is present when the player uses the mobile phone before dying from falling into a pit or by touching dangerous surfaces which will cause the game will freeze up. This glitch can also be caused by getting the ability roulette (when one of the other Kirbys uses Magic and the outcome is that everyone gets an ability roulette). This glitch was fixed in the International version.