You know you’re in trouble when a grand new production of Verdi’s “Aida” only catches fire midway through the second act, after the “Triumphal March”—when Amonasro shows up.

“Aida,” which premiered in 1871 at Cairo ... the tomb in Act II — a processional theft set to the tune of the “Triumphal March,” and one of the most bizarre instances of interruptus ...