Errors do happen. As they are caught, they'll be corrected in the next update (this is another benefit of self-publishing an e-book), but in the meantime, you can find them listed here.
The first edition of the book (for Yii 1) is now in maintenance mode, which means new releases will occur rarely, and only for significant problems. Almost all of my energies will go towards the second edition of the book (for Yii 2).
If you catch an error in the book, you can submit that via the feedback page. Thanks!