OK, I think Sweet Sweet Canyon isn't in the Luncheon Kingdom, partly because of the largely different aesthetics, but mainly because I think it is a normal cake, not a giant one, and the racers are shrunk down to race on it- Maybe Bowser got his minimiser back out or something- the same way as Ribbon Road. I'd also like to point out that the surroundings of Sweet Sweet Canyon feature Princess Orange bottles (Which can be seen at normal size in the Super Bell Subway vending machines), and Peach & Daisy Royal Patisserie logos everywhere (Outlets of the patisserie can be seen in Yoshi Circuit and Toad Harbour). I think the course is made by the patisserie, seeing as it features a large number of their boxes and cookies. Also, Sweet Sweet Canyon is inhabited by gingerbread cookies and pink Piranha Plants (I'm excluding the Yoshis as I presume they were also shrunk, they don't really fit in with the aesthetic), neither of which appear in the Luncheon Kingdom. Also, the only liquid that appears in Sweet Sweet Canyon is Princess Orange, which is not seen in the Luncheon Kingdom.