If I'm not mistaken, you have to be a citizen of the European Union.
Also, how could facebook verify that you're a citizen or not, couldn't you just say you were always a citizen, just on a greencard in the US for a few years?
Would it be illegal to show facebook a fake id?
Just idle curiosity.
So it’s retroactive.
Facebook doesn't have much to do with that, the creation or possession of a fake ID can already get you in trouble even if you never use it at all.
This is highly dependent on where you live, better check your local laws.
Almost certainly. That's lying for personal gain, i.e. fraud.
Disclaimer: I am not a lawyer. This is not legal advice. Don't do fraud.