In Ireland I have no clue what the laws are. HOWEVER, there is precedent in other countries of American publishers suing foreign nationals for copyright infringement and basically dragging them to an American court.
Word of advice, if you're worried about, don't do it. If you do it, then don't charge money for it. My biggest peeve when people steal my property (I'm a producer/publisher) is when they try to make money with it. There are a lot of games floating around using my property and I'm good with it until they start charging for it. (or start whining about other people stealing their work when 90% of their work is already stolen)
On the flip side, if you alter the images sufficiently enough, like in Good Girl Gone Bad a case MIGHT be able to be made that they're no longer the original image. It's an entirely new product. That however seriously depends on the lawyers and the court.
Another flip side, it also depends on how far someone is willing to protect their property. Me myself, barring what I've mentioned above, I have no problem putting someone on the moon into bankruptcy if my lawyers tell me they think they can win and I don't care if it costs me more than what I'd win. Not everyone is like that though.
TL;DR: If you use any copyrighted images, music, code, anything. DO NOT charge money for it. No donations, no excuses. You're more likely to have the rights holder take umbrage and when you lose, you're gonna lose big. Some, like myself, will ignore you until you start trying to make money off it.