In 2022, a pair of previously unknown cheat codes for the game were discovered, presumably having been used for debug purposes:

• From the title screen, by holding the R and Y buttons on a second controller, and then pressing Start or A on the first controller, a new menu will appear showing Little Mac versus head profiles of all 16 fighters in the game, allowing you to select whoever you want for a one-off match. After the match is finished, you are sent back to the same menu.

• Also on this menu, an unbalanced two player-mode can be accessed if the second player holds B or Y on their selected opponent until the match starts. As the opponent, using A, B, X, or Y in tandem with Up and Down will allow you to pull off every basic and advanced attack in each boss's arsenal. This mode is unbalanced in that every boss is still more powerful than Little Mac and have pauses with "tells" for when they are about to attack, and if dodged successfully will leave them vulnerable to attacks.

Charles Martinet provided all the voice work for the game.

In prerelease photos and trailers, Little Mac still had his original NES Punch Out design. It is unknown why or when it was changed.