Those who passed by were various spectators and part of the crowds of people going to and coming from the city; they were not the soldiers. So “people who went by there” may be good.

Derided is translated “hurled insults” by Good News Translation and New International Version, while New American Bible has “kept insulting.” The Greek verb is the one traditionally rendered “blaspheme” when God is the one who is insulted (see 9.3; 26.65).

Wagging their heads indicates scorn or insult (see Psa 22.7; 44.14; 109.25; Job 16.4; Isa 37.22; Jer 18.16; 48.27). The significance of this gesture may not be understood, so translators have either used a word that will show derision (Barclay has “tossed their heads at him”), or have combined the two ideas in the verse, as in “wagged their heads to insult him.”

Quoted with permission from Newman, Barclay M. and Stine, Philip C. A Handbook on the Gospel of Matthew. (UBS Handbook Series). New York: UBS, 1988. For this and other handbooks for translators see here .