The Archers, with their feathered helmets, resemble the Valkyries of Norse/Germanic mythology.
This is the first time in the series where Alcmene's name is spoken on screen.
Some of the other children of Echidna were - Cerberus, The Chimera, The Nemean Lion & The Sphinx. Technically in mythology they are all related to Hercules/Heracles by blood.