As I recall the "fake" Pan Am did have some Carribean routes. Even now they appear to fly to SDQ and SJU (although the latter could be called domestic) in checking on http://www.flypanam.com/ although not via Miami. But I don't know about the routes the OP mentions and can't recall this incarnation serving MIA in the past. Could also have been a charter looks like. Or it could have been the wrong date.