I knew a Japanese-American fellow that was always being mistaken for Mexican.
I can't imagine mistaking a Japanese person for a Mexican. However, on a vacation in northern Minnesota, my first, thoughtless reaction on seeing Ojibwe Indians everywhere was "why are there so many Mexicans in northern Minnesota?" Since most Mexicans have more American Indian than European blood, I guess it's an easy mistake to make.
Same with a friend from work. He was Japanese and had people talk to him in Spanish all the time.
My mom was Mexican (ancestry), and in her elder years, she was mistaken for my Chinese sister-in-laws mom. And I saw a Chinese woman at an asian market who could have been my mom’s sister.
Based on MtDNA, my mom had almost 60% native halogroup origin, with the highest concentration amongst Peru and Bolivia. B2b MtDNA.
At the sushi place I noticed Asian looking Mexicans are the new itamae.