Factual error: When Firestar, Ravenpaw and Greystripe are helping Mistyfoot, Featherpaw and Stormpaw escape the Tigerclan camp, it says: "the whites of his [Greystripe] eyes bright in the half light" but cats' eyes don't have whites. Their eyes are all one colour eg: orange, yellow, green. with a black pupil in the middle.
Continuity mistake: When Firestar holds the ceremony so Greystripe can continue Stormpaw's training, it says: "Leaping down from the Highrock he beckoned to Stormpaw with his tail." but further down the page it says: "Firestar brought the meeting to an end and descended from the Highrock", despite having already descended in the earlier sentence. Also on that page, "Highrock" is spelled as one word but further down as two. Throughout the rest of the book, it is one word.