There are three unused enemies hidden in the game's code. These are CzarDragon, Colossus and an alternate Umaro. The Colossus and Umaro use the same graphics and palettes as other enemies in the game. The Colossus is fairly simple and has a full attack script, and the alternate Umaro is weaker than the original.

CzarDragon however has no script, so when the battle begins, all it does is attack repeatedly. Which is odd, as there's a line of battle dialogue for the enemy, as though it was intended to be fought. The dialogue reads:
Mwa, ha ha... Humans and their desires! I'm free at last! I bring you destruction... I bring you terror... I am Czar... Prepare yourselves!
Taking into account the dialogue and its likeness to Shinryu in Final Fantasy V, it seems as though CzarDragon was intended to be an optional end boss. In the Gameboy Advance rerelease, CzarDragon can be fought under its original Japanese name Kaiser Dragon. It has a unique sprite similar to the SNES design.