User blog comment:Menara/The Son of Sobek: The official PJ and Kane Chronicles Crossover/@comment-90.149.162.73-20130507161935/@comment-3146930-20130508234722

Just a couple counter points:
 * Yes the Doors of Death are mentioned at the end of The Last Olympian, but Percy didn't learn that souls were using them to escape until The Son of Neptune, where Nico explained that monsters were using it to reform and Mars explained that souls were using it to escape. In the story, Percy immediately accuses Carter of being an escaped soul.
 * If the pegasus Carter saw was during the Battle of Manhattan, then this story would have to take place some time before The Son of Neptune, as Carter mentions seeing it a year ago. If it was between The Last Olympian and The Lost Hero, Carter would have only seen it a few months ago. He could have also seen it during The Titan's Curse, but even a year later Percy wasn't able to make hurricanes like he did in the crossover.