The dialogue. I mean, I don't think the writer ever considered that a top-ranking Ninja would never say "YAHOO!" upon receiving his "black belt" (which I'm pretty sure Ninjas never used as rank). And why am I capitalizing ninja? Because the author does.

And the way too specific comparisons that a man raised in Tokyo, even with an American-born father, would never know; like comparing a group of large men wishing to brawl to the Dallas Cowboys. Something tells me Ryu didn't read up on American football while spending his life attaining perfection in the arts of Ninjutsu (which never appears in this book as the actual term for what Ryu practices, probably because the author never bothered to look it up).

I understand that these books are written for a young audience, but don't we feel it necessary to use any form of accuracy in a story that involves real things like ninjas? Even those based on a video game. ( )