Knuckles the Echidna in Sonic the Hedgehog 2/Bugs

Knuckles the Echidna in Sonic the Hedgehog 2 introduces a small handful of new bugs not found in the vanilla version of Sonic the Hedgehog 2.

Level bugs

Aquatic Ruin Zone

Red water

In vanilla Sonic 2, the surface of the water uses Sonic's palette line for its blues. As Knuckles is red and the art wasn't changed, the water also becomes red.

Not fixed in any version.

Hammer Eggman

It is possible for the game to continuously give you arrows in topmost and/or bottommost slots of the totem poles. Due to Knuckles being only able to jump either from the ground up to the top-but-one or from bottom arrow to top slot, this results in not being able to win the boss fight without the loss of a life.

If you can get on top of the left pole, you can spindash (fully charged) into Robotnik AND return to the pole. This doesn't work on the other pole. This makes a very cheap tactic to win, but it is used by speedrunners to defeat this boss quickly.