The game was meant to be longer, but due to time constraints, the high manufacturing costs of a 34 megabit cartridge with NVRAM, and Sega's commitment to a major McDonald's Happy Meal promotion featuring a sweepstakes to win a copy of the game, the decision was made to split the game into two games, Sonic the Hedgehog 3, and Sonic & Knuckles. Evidence of this split can be found in the level select menu (sound test), where levels from the second game (such as Flying Battery, Mushroom Vally, and Sandopolis) can be found.