Dirce says to Queen Melissa "You're an uncommonly beautiful woman." Lisa Chappell plays both characters.
At 19:30 Dirce states "It's always darkest before the dawn". This concept was first expressed by the English theologian and historian Thomas Fuller in 1650.
Early on Iolaus is telling Hercules about "Eureka" and "...any object would displace its own mass in water." Archimedes was asked to determine if an ornate crown was pure gold. For that he needed to determine the density (weight/volume) of the crown, but because of the crown's shape he couldn't easily measure the volume. The common notion is that he realised that immersing the crown in water and measuring the rise in the water level would give you the volume of the crown. The real solution Archimedes had probably involved immersing the crown and an equal weight of pure gold in water on balanced scales so as to directly compare densities.