What can I do if a photo I posted on my Facebook was used without my consent in a for-profit film?

Interesting question, I'll be interested in what people here will answer.

Is the for profit film a documentary? If so, then it is probably considered "fair use". If it's not a documentary then they probably can't use it.

I don't use Facebook so I'm not familiar with their policies but I have heard some discussion about them. From what I understand it is their policy that they can use any photo posted to Facebook internally but they say they don't share them with outside sources without consent. That kind of sounds like it would make it easier for someone to grab the image from somewhere without knowing exactly where it came from.

You should contact Facebook with evidence of the photo's use.

I'm no expert but I have vague opinions.

On privacy - the fact that it was on facebook limits your case - if they could view it without being your friend then lawyers would probably argue you had no expectation of privacy - however if your privacy settings were such that you had restricted access to the photo and one of your 'friends' broke that restriction you might have a case against the friend - or if the documentary makers hacked into your account then that would be illegal (I'm guessing)

On the matter of intellectual property you would probably have to argue how their use of your photo deprived you of income generated by the photo. Social media being what it is (and not knowing the specifics) - that would probably be hard to argue - in fact often the opposite may be true, in that drawing attention to the photo provides you opportunities to derive income.

If you're really concerned seek 'real' legal advice - I'm probably not even from your country.