The Atari 7200 port contains text hidden in the game's coding, which reads "MOMMY AND ME ARE ONE." This text is a paraphrasing of a 1985 experiment on the effects of subliminal messages on the unconscious mind, where the phrase "Mommy and I are one" was allegedly effective at raising self-motivation.
At the end of the game, the player is meant to approach the princess in the stand-by/running mode to end the game properly. If the player enters a fighting stance and then approaches the princess, she will kick them, thinking you are an enemy, which will kill them in one hit.
Playing the B-side of the disc would make the game play upside down.