I started plowing through the document finally. Since I didn't find a dedicated topic for errors, I'll post the first batch I found.
pg. 2. "Dwarfen captain" should be "dwarven captain" for the sake of consistency.
pg. 4. "Not only does this remove the number of fiddly additions and subtractions, players have to do, but it means that when modifiers are meaningful and have a significant effect on play." There is no need for comma after "subtractions", and the second part of the sentence doesn't need that "when".
pg. 5. I would add to the "A Set of Polyhedral Dice" section a mention of