An unused character dubbed "Yummer," who appears to be a humanoid monster with a realistic, smiling mouth and set of eyes, can be found on one of Mrs. Puff's sprite sheets in the Krusty Krab as well as another Krusty Krab sprite sheet featuring Mr. Krabs and Incidental 106, the latter of which contains what appears to be an alternate pose for Yummer, indicating that it may have had an animation at one point.
In the game's library.json file, Mrs. Puff's first sprite sheet is defined as "t_tmpYummer," which is believed to be the name of the monster.
The creator of Yummer (whose original name was "Yum") later stated that Yummer was a 3D-modeled placeholder.
Plankton and Karen appear in this game, but they are the only main characters who do not come to SpongeBob's party at the end.
To get rid of Plankton and Karen, the player uses a bucket of water to drop on Karen, making her malfunction and zap Plankton. Oddly, the sprite used for the bucket is a Chum Bucket bucket helmet, which Plankton and Karen use for their own evil deeds. Also, Karen is a waterproof computer that lives underwater, so water should not have this effect on her.