Off of the top of my head:
1. In Spain, the milk and eggs you buy at the grocery store doesn't have to be refrigerated.
2. Even though they say "the rain in Spain falls mainly on the plains", it actually mostly falls in the North.
3. At one point, the Moors from Africa conquered all of Spain except for the northern region of Asturias. The prince of Spain is called the "principe de asturias" because of this.
4. Spaniards don't consider themselves as speaking "Spanish". They call it "Castellano", or Castilian, instead.
5. In Basque country in the north of Spain and southern part of France, native Basques speak "Euskara", which is such a strange language that linguists can't figure out what its roots are. To say I love you in Euskara is "Maite zaitut".
6. Spanish olive oil is much better than Italian olive oil. This is why Italians buy all the spanish olive oil and send their oil to the United States.
7. People in Spain don't eat tacos, burritos, enchiladas, quesadillas, tortillas, or refried beans. It's pretty hard to find these foods there. (Some people are surprised at this).
8. The longest bench in the world is in Parque Guell in Barcelona. It is maid of cement with a tile mosaic.
9. In a church in the city of Ourense, they have a crucifix hanging above the altar that is actually a mummified dead body that is hundreds of years old. People there believe its hair and fingernails continue to grow.
10. At Kentuck Fried Chicken in Madrid, you can't get mashed potatoes - they have french fries instead.
Lived in Spain for two years