Unfortunately, over the past few years, we have made a few errors. We work hard to make sure this does not happen, but we do occasionally let a few errors slip past us.
We try to correct these as soon as we note them. Corrected versions of the PDFs can be downloaded from DTRPG free of charge. If you go to your Account page and then look at the first section called "Library", you will see a section titled "Updated Products". There you go see the products which we (and other publishers) have updated since your purchase.
Sometimes these are small errors that escaped our attention, other times the errors are larger than we'd like to admit. For instance, a short time ago, we noted that a page in SS4: Sequoyah was inadvertently replaced with a page from SS3: Hub. That has now been repaired.