Quick run-thru, this is what I found.
Looking at dates in the chapter headers. Should be 20 New Imperial Year (4132, Year-of-the-Tusk):
Chapter 2 (pg. 56): date is wrong, says 4123
Chapter 9 (pg. 241): date is wrong, says 4123
Section break graphic, pg. 218, is smaller than normal.
Section break graphic, pg. 356, is different than rest of book.
Yearly times: Aorsi (chapter 4) says Early Autumn, next GO chapter (10-Dagliash, pg. 267) says Late Summer. (s/b Early Autumn?)
Again, 13-Dagliash, pg. 334, says Late Summer (s/b Early/Mid Autumn?)
Again, 15-The River Sursa, pg. 411, says Late Summer. (s/b Mid Autumn?)
17-The Demua Mountains, pg. 462, says Late Summer. (s/b Mid Autumn?)
{{Kellhus arrives back in Momemn in Mid Autumn (according to Momemn chapters), AFTER the bomb. Calls into question the above times of year.}}