Autolycus poses as a statue of Hermes, the Greek messenger god. He says the mercury dust is affecting him. Mercury is the Roman god equivalent to Hermes. Hermes/Mercury is Autolycus' father in the myths, although not necessarily in this series.
Sam Jenkins aka Sam Sorbo refused to reprise her role as Serena, due to unpleasant experiences with the Golden Hind makeup. Kara Zediker took her place.
Ares says, "And the present day Hercules is off trapping the Erymanthian Boar." That was the fourth labor of Hercules, the third had been capturing the Golden Hind of Artemis (which did not have a quasi-human appearance in the myths).
Hermes/Mercury was not only the patron god of messengers, merchants, athletes, and travelers but also of thieves. He wore winged sandals, a winged hat and carried the caduceus, a winged staff with two snakes twined about it.