In this post I'll try and keep a running edit with a master list of Errata. Please report anything you find to this thread.
13th Age Core Rulebook
(p.40) Should read: Each character gets 8 background points, though the bard, ranger, rogue, and sorcerer have talents that award bonus points.. Currently it lists wizard in that list, which is incorrect.
(p.140) Breath of the Black Dragon attack should be against PD not MD.
(p.153) Charm Person Attack should be Intelligence + Level vs MD instead of using Charisma as it's attack bonus.
(p.205) The monster list is missing (at the end) the entry for Huge Red Dragon, 13th level Wrecker on page 223.
From the Archmage SRD:
Gnomes have a +2 AC bonus against opportunity attacks. -- Should read "Halflings"