Had no problem with the Spanish at all.
They dub all the films here in Germany so very often you have to wait for the DVDs if you want to watch the original versions :x
Although I saw it not too long ago, what really sticks for me are the visuals, especially the fairy creatures, and then that extremely violent and cruel Spanish officer. The rest seems to get blurry rather quickly.
Don’t know where they shot it either, I’m afraid. Comrade Internet might help.
It’s definitely a film worth watching, although the formula didn’t quite work out for me. My favourite Spanish movie is El día de la Bestia. Fuerte!