So much like how it didn't take us long to find all the small things in The Son of Neptune didn't add up (like how Percy said Hera took 8 months instead of 6), with The Mark of Athena out, we can find all the little mistakes Rick made. While I have found at least 3 or 4 obvious ones already, have you all noticed any? If you find any mistakes with the book that don't add up with the previous books or simply events in the book themselves, feel free to share. If it isn't a plot hole, then someone will correct you.
So to get the ball rolling, here is a very obvious one:
- Reyna told Annabeth that Hylla had left that morning. However Hylla was at the Senate meeting when the Argo II arrived at the end of The Son of Neptune. So if she did leave, she left as the ship was landing.