believe it or not, there's actually calories from alcohol.... but i've always wondered the same thing... that is why the nutritional facts labels aren't mandatory for such products.
To put things in perspective... there is appx 4 cals per gram of carbohydrates, 4 cals per gram of protein, and 9 cals per gram of fat.
And as for alcohol: there are 7 calories per gram of alcohol. besides beers and wines (which are loaded with carbohydrates), pure grain alcohol is appx 200 calories per ounce of alcohol. there is some equation considering different proofs.