In the episode, was it ever stated that the Broken Bow inthe episode was the one that is apparentely in Oklahoma? If not, looks like another case of fanon-itis.
Besides that, I have never given a thought to whether or not Broken Bow is a real city or town or which state this possibly fictional town may or may not have been located in until looking at this thread.
Further, in the event BB was actually supposed to be the one in Oklahoma, knowing that one of our posters didn't see any cornfields on his recent trip there somehow has had no effect on my enjoyment of that episode.
BTW, I enjoyed the Episode and most of Enterprise. I just noticed they were not there. But it is a nice place to visit if you want to get away from the city for awhile.