Sure, the Pythonalia is all there. But it all has undergone a drastic sea change, too — crossbred with a century’s worth of Broadway conventions, and with bits of additional genetic material lifted from Las Vegas and Super Bowl halftime shows, from pop music sound bites and the trans-Atlantic trills of Andrew Lloyd Webber. A wacky hybrid (with Broadway proving to be the dominant strain, especially in the show’s second act), it has arrived with such a blindingly bright sheen — and at the same time with such a sense of the loopily quirky teamwork that made the original Pythons who they were — that you don’t know whether you should sing ”Hail to the Queen,” ”The Star-Spangled Banner,” ”Havah Nagilah” or ”YMCA.”