Well, according to this site, there are currently 202 NOCs. Assuming the alphabetical country listing for the opening ceremonies accurately lists those countries that participated, then the 202 on its list seems to indicate participation by every NOC.
The ceremonies list shows Greece twice, but North Korea (PRK) did not march separetely from South Korea (KOR), so their total should still be correct.
The local commentators here mentionned that no nation refused their invitation for a record 202 participants, so it would seem the answer is “no, everyone showed up”.