A hidden Easter egg in the game is accessible by going to the status screen and holding down and left on controller 2, and pressing right and select on controller 1. This will bring up a screen with two mugshots and Hiragana text under each that says "Kunio" and "Riki," as Double Dragon theme plays. This is only available in the US version of the game. The cheat can be executed on the European version as well, but the mugshots and texts will be replaced with pieces of the title screen, as the assets were overwritten in localization.
Contributed by KidDivinegon