im assuming u looked where the rear speakers are supposed to be mounted? if not, id start there. i really dont know anything about Hondas, but i would say if there is nowhere for a speaker to mount in the rear anywhere, then it probably doesnt have rear speakers. it is quite possible that the harness they use is just a generic civic harness and has rear speaker wires even though there may not be any. again, i dont know much of anything about Hondas, but just a suggestion.
EDIT: i just checked crutchfield, and they are calling for 5 1/4" speakers in the side pannels of the rear passenger compartment, so there should be something there.