Whatever the crowds streaming through Wynwood Walls at Saturday’s art walk were expecting — colorful murals, free wine — they didn’t expect this: a phalanx of sultry dancers moving in taut unison to seductive tango music, a sensual dance fantasy emerging suddenly from the mass of shuffling art viewers.

“Wow, they’re good,” asked one woman, eyeing a line of lean men over her cellphone camera. “Who are they?”

They were members of Miami City Ballet, in their first flash mob performance. Their surprise show, an excerpt from Paul Taylor’s Piazzolla Caldera, aimed to promote the ballet’s season-opening program at the Adrienne Arsht Center for the Performing Arts this weekend...