The first printing of Fantasy Flight's Mansions of Madness, unfortunately contained several game spoiling errors and misprints in it's rules and cards. Fantasy Flight's updated, as of 6/3/2011, Errata and FAQs now states that these errors have been corrected in the second printing, which can be recognized by the MAR11 printed in it's barcode. Unfortunately the second printing has some errors of it's own.
The updated errata also confirms, as many gamers predicted, that a corrected set of cards will be included in an expansion, stating:
While some errata has been revised in the second printing of the game, we will include a corrected set of all known misprinted cards in the first (non-print on demand) Mansions of Madness expansion.
The full Errata and FAQs can be found here.