Who are the passers-by?
Since the crucifixion took place in public, the ones who pass by are most likely ordinary people on their way to and from work and other errands. They may be members of the Sanhedrin or court attendants who had been privileged to sit in on the hearings/trial of Jesus.1
29 And those who passed by derided him, wagging their heads and saying, “Aha! You who would destroy the temple and rebuild it in three days,