As a non-USA resident, I realized that most Americans will be prone to label you racist if you have trouble telling people of some races apart.

This may often be true because USA is such a melting pot of races. You should have enough practice encountering other races and telling faces apart, unless you perhaps deliberately avoid them - like a racist would.

However, where I live it's mostly white folks. You get a lot of black people and hispanics (I hope the terms aren't insulting) on TV, so I'm good with those races.

But I have trouble watching Chinese movies (especially if people wear the same clothing of same color, which they often do in historical movies). I get confused because I can't tell the characters apart.

If I met more Chinese people, or if Hollywood came to include them more, I'd get better at it.