The background used on the title screen in the Japanese version has a very small depiction of what appears to be an Ai-Ai Gasa (相合傘; translated as under one umbrella) saying "Mario" and "Peach", as well as Japanese text saying "Mario Kart". These were later removed internationally, presumably for their small size and language, and the mushroom was moved to fill some of the resulting dead space.
Here's a close-up of the removed umbrella drawing, which has "マリオ" (Mario) and "ピーチ" (Peach) written underneath it. Similar to how in America we draw a heart and write two names inside it, Japanese sweethearts draw what's called an ai-ai gasa ("love-love umbrella").
