The 8-bit version of Sonic the Hedgehog 2 has two endings:

• A good ending, played if the player collects all the emeralds, where Sonic and Tails run off together at night, and see a constellation in the shape of their heads in the sky.
• A bad ending, where Sonic runs alone in the night, and sees a constellation in the shape of Tails' head in the sky

Although it has never been confirmed, many fans have speculated that the bad ending is supposed to involve Tails dying at the hands of Dr. Eggman, with some even going as far as to suggest that a large star on the right of Tails' forehead is supposed to represent a gun wound. The @sonic_hedgehog Twitter account has jokingly acknowledged this theory without confirming one way or another if it is true. Once in a cross-promotion for The Murder of Sonic the Hedgehog and the 8-bit game's addition to Sonic Origins Plus, where it compares both games' inclusion of "a beloved character's possible demise", and in a piece of promotional artwork taking place at a carnival, where Tails gets nausea on an intense ride and his constellation can be seen above him, with the "gun wound" star being placed on his muzzle.

The Game Gear version of Sonic the Hedgehog 2 has a reputation as one of the hardest installments in the Sonic franchise due to making minimal changes to already-challenging level layouts designed for the Master System's larger aspect ratio on the notoriously small Game Gear screen.

Because Sega prefers to release the Game Gear version of the game on newer hardware, and the original Master System version only being released in the Master System's most successful regions (Europe, Australia, and Brazil), most players are only familiar with the version generally considered inferior.