I’d love to tell you I had some deep revelation on my way down, that I came to terms with my own mortality, laughed in the face of death, et cetera.

O.o  Why would you want to tell us that?  What even is the motivation behind this line?  Are there lots of stories out there about people figuring out the secret to the universe right before they die, and the author decided he wanted to subvert that?

After assuring us that he did not have a life-changing revelation while falling, Percy lands in the water and ends up perfectly fine.  The water even fixes the poison from the chimera sting last chapter.  Then Percy notices that, even while at the bottom of the river, he’s perfectly dry and can breathe normally.  So…is this a new thing, or did Percy just never notice before that he got out of his showers perfectly dry and just as rank?  Is this because Poseidon is changing how water reacts to Percy, or some virtue of Percy’s demigod-ness?  The issue isn’t addressed, and Percy doesn’t even think about how water used to act around him, in comparison to how it’s acting now.  What’s causing the change, if indeed there is any change at all?

Some unknown, unseen, female-ish presence starts talking to Percy through the water, telling him to go to Santa Monica Pier before he heads into the underworld.  So Percy swims out of the river, where he sees off in the distance there’s a lot of emergency vehicles around the Arch.

A little girl said, “Mama! That boy walked out of the river.”

“That’s nice, dear,” her mother said, craning her neck to watch the ambulances.

“But he’s dry!”

“That’s nice, dear.”

Really?  I know there are parents this dismissive, but the text seems to be treating this as your average, everyday sort of thing.  Parents aren’t actually this dismissive on average.  If a child says “Mommy!  Mommy!  Mommy!” and nothing else, sure.  But children don’t actually make up stuff out of the blue very often.  If they do, it tends to be in specific scenarios where, like playing with toys.  A kid that says “some boy just walked out of the river” is saying so because they just saw a boy walk out of the river.  And parents know this, because kids don’t walk around on average pointing out things that aren’t happening. 

Percy overhears some reporter talking about the ‘terrorist attack’ which was set off by ‘an adolescent boy’ who went ‘wild.’  But what about the monster?  I know, I know, ‘Mist’ and all that.  But the Mist is supposed to turn the monsters into something humans can deal with.  That’s why they’re in disguise in the first place, instead of just walking around looking like monsters: because people can actually see them.  So why did none of the witnesses see Percy fighting something, even if they thought the ‘something’ was a huge dog or what-not?

And why call it a terrorist attack and say that it was set off by a teenager in the same breath?

In fact, after Percy walks around and finds Annabeth and Grover, he even overhears one of the witnesses talking about a ‘fire-breathing Chihuahua.’  Obviously, the authorities aren’t going to believe that Chihuahuas can breathe fire, but they are going to assume that the person saw something and just got confused, not that the person hallucinated a source of the fire. 

In fact, if anything, this sort of talk would produce an assumption that’s closer to the truth than a fire-breathing dog.  They’ll probably assume there was some sort of bomb disguised as a pet, because that’s the closest thing that makes sense and still fits what the witnesses are saying.

Except in this book, where the police see Percy and start chasing him, because clearly ‘fire-breathing Chihuahua’ = ‘the teenage boy did it.’

Well, ‘chasing’ in a general sense.  Percy doesn’t actually get chased in this chapter, he just meanders down to the train station and gets back aboard.  Apparently all this happened in under three hours.  Go figure.