According to Ohr HaChaim the erev rav were spies sent along by pharaoh to sow seeds of dissension among the Jews. The erev rav is a concept and a title given to any Jew (descendant of Abraham)  who tries to dissuade other Jews from belief in the Sinaitic Torah. (ie. not the Talmud) The motto of the erev rav is in Sh’mot 32:4 “These are your gods, O Israel, which brought you up out of Egypt.”  Gematria of da’at and ‘erev rav = 474