When Iolaus meets his stepfather for the first time, the latter is holding a leather bound book rather than a scroll. Another (doubtlessly deliberate) anachronism.
Zeus' father, the Titan Cronos (also spelled Kronos or Cronus), gets a few mentions, and Ares alludes to Cronos' father, whom he does not name. Cronos' father in the myth was Uranus, whose name is hard to pronounce in English without sounding sophomoric and giggle-worthy. The original Greek spelling, which English-speaking popular culture has overlooked (perhaps deliberately) is Ouranos or Oranos.