An Obvious Error in the Dialogue
I'm surprised nobody has mentioned this before:
Valerian: "Twice each year, at the Spring and Summer Equinox, the king selects a new victim. Virgins."
There is no such thing as a Summer Equinox. There are the Spring (Vernal) and Fall (Autumnal) Equinoxes, and then there are the Summer & Winter Solstices.