I was basing my answer on the fact that the full-screen dvd releases of 1,2 and 4 are Open Matte but POA is pan and scan, although this is not conclusive it would be a very odd choice if it was filmed on super 35, perhaps IMDB is wrong because people have assumed they are all the same, or maybe it is super 35 but it was pan and scanned because the effects weren't done in full-screen as they were on the others. see here for details on the framing of the fullscreen dvds.

Also I seem to recall that all the screenshots I've seen from previous airings of POA in HD have been cropped down on the sides.