Gallery:Sponsors in the Mario Kart series
From the Super Mario Wiki
The Japanese version of Mario Kart 64 features several sponsors whose names and logos are puns on real companies. These sponsors are "Luigip" (pun on Agip), "Marioro" (Marlboro), and "Yoshi 1" (Mobil 1). Also, the Japanese version of the "Koopa Air" logo has the color scheme of Goodyear's. These were taken out in the English version, presumably to prevent lawsuits of the companies (and tobacco references in the case of "Marioro").
The "Shot!" logo, even in the American version, seems to bear some resemblance to that of Shell, largely due to the similarity of the names (it can also be considered a pun that the logo is a Koopa shell, though Shell's logo is a stylized seashell).
The trucks on Moonview Highway have ads for Toad's Factory, Coconut Mall shops, and the Moo Moo Dairy. The other ads can be found on the sides of the tracks. In several cases, the faces of characters will swap with a random Mii's face from the player's system if a Mii is part of the race.
"Shy Guy Metals", as seen on some banners, is a Shy Guy mining business taking place in the Shy Guy Falls course. The banner also reads "since 1987", possibly referencing the launch year of Yume Kōjō: Doki Doki Panic, the game that introduces Shy Guys. Additionally, the logos that appear in Mario Circuit also appear in the stage of the same name in Super Smash Bros. for Wii U. One of the Women of Racing Organization signs has Birdo on it, despite the fact that she does not appear at all in the game.