On Dribble.comChris Bishop made a post about new karts are going to released. They were released in 2018. But, they could also be secret codes we don't know yet. The teal square depicts, whom we now know as, Pinewood, the new character coming to Kart Kingdom. This could possibly mean that it will be possible to get that Kart and mouth. Or, maybe these aren't new karts, but new characters. A lot of users are happy about the new characters and items that are coming to the game.
On July 1, 2017 and September 11, 2017, SirGawain8 and Yumms567 found these in the game files of Kart Kingdom. Sussettey1 then tweeted them to Chris Bishop asking what they were for and he said most of it is for something really big they are working on. Other unreleased karts were found too.