Temjin from Art of Fighting 2 and Jin Fuha from Art of Fighting 3 make a cameo appearance as co-hosts on the Satella News Network interlude.

Baitang from Real Bout Fatal Fury Special appears in the background of the China stage.

There is character data for Vice, Hwa Jai, Takuma Sakazaki, a boss, Dark Ash, Mai Shiranui, King, Yuri Sakazaki, Classic Iori, Billy Kane, and 7 empty slots within the game's code. Making that a total of 17 characters planned for the final version, 10 that had made it to planning and 7 that never even made it to the data.

Prior to the game's console release, SNK celebrated the series' 15-year anniversary by updating the official King of Fighters website to feature images of K' and Mai Shiranui in the game's art style. This led to speculation that the two characters would be playable on the console versions of the game. This ended up being false, with both K' and Mai becoming absent from the final roster, with Elisabeth and Mature substituting as console-exclusive characters.

Athena's design was drastically changed for this installment. According to SNK illustrator Eisuke Ogura, Athena's character design was revised many times over until the design that appears in the final game was reached. When drawing her, he kept getting comments like, "She let her smile!" or "Make her legs fatter!" or simply "Fatter!"

Many of the spectators in the background of the France stage are obese, well-dressed women that are dining while excitedly watching the match. The idea for these NPCs was inspired by a posh French resort that is known for attracting wealthy tourists, and was not intended to stereotype French women as being fat.

According to Ignition's Director of Business Development, Shane Bettenhausen, the decision to revert many of the older characters back to their classic designs and moves was an aesthetic choice:

"To go along with the game's central 'Rebirth of KOF' theme, the designers purposefully returned to the classic KOF '94 costumes and move sets for many of the returning fighters."

Elisabeth was featured in an early promotional poster for the arcade version of the game despite being a console-exclusive character. The same poster also features Leona in her original outfit from The King of Fighters '96 when she was redesigned in the final game.