In the case of Cuba, you just have to make sure you have enough cash on you for the entire trip. Or have a foreign bank account. If you're there without a permit (I never was) and the shit hits the fan, you can take the walk of shame to the U.S. Interest Section in Havana, where you'll be bailed out of most messes and then promptly reported to the Treasury Dept.

In the case of Haiti, one would be fortunate to live long enough to ask directions to the Embassy.