In an SBS, Oda decided to draw the whole crew, Gender-swapped.
This is a close approximation of what he did.
He also listed the assumed Nationalities of each of the crew members.
Luffy: Brazil Zoro: Japan Nami: Sweden Usopp: Africa Sanji: France Robin: Russia Chopper: Canada Franky: America (Almost definitely referring to USA, probably) Brook: Austria
True, but it's a common mistake to make, one that bears no real malice just some basic slip into the all too human error of 'not thinking' things through. I've yet to meet anyone who can correctly indentify every single country that 'Africa' comprises of. I'm sure there are plenty that could though.