New South Wales
Yep, it's probably the four extra Flesh Wards that replace those from the base game. It's explained just after the component list:
Dunwich Horror Rules wrote:
To improve game play, several Arkham Horror cards were revised after the release of the base game. These revised Arkham Horror cards have been included in this expansion for your convenience. The revised cards are: four copies of Flesh Ward (a Spell), one copy of Healing Stone (a Unique Item), and two copies of Lantern (a Common Item). To use them, simply remove the old cards from your Arkham Horror card decks and replace them with the revised cards before playing.