Within the series, books and movie, there are several mistakes, claiming one thing at one point, yet something else in another part:
- In The Hatchling, Otulissa reads cantos from the The Fire Cycle. It explained how the Wolves of the Beyond migrated to Beyond the Beyond, this took place before the The Legends of Ga' Hoole. In the prologue to The First Collier, Ezylryb claimed the The Fire Cycle happened after the Legends of Ga' Hoole.
- In The War of the Ember, The Striga was referred to being a Spotted Owl, but it is also mentioned earlier that he was a Snowy Owl.
- In Exile it is stated that Ruby went to the Northern Kingdoms because she had not been there before, but in The Burning she went with Martin to find Hoke of Hock.
- In To Be a King, it is clearly stated that Lord Rathnik died in the Battle of Short Light, yet strangely enough in "Theo's Story" in A Guide Book to the Great Tree, Lord Rathnik was mentioned to be next to Ivar when he crash-landed into the Ga'Hoole Tree. This took place some time later after the battle.
- Wortmore was killed by Slynella's venom in The Siege, yet he asks Nyroc to attend Kludd's funeral in the Hatchling and is mentioned in The Golden Tree. Either that was a different Wortmore, or the sea wore off the venom's effects.
- The Others were mentioned as being during the time of the first owl, but since Glaux was the first owl and many owls exist during the time of humans, that couldn't be. The owls probably exaggerate time.
- In The Capture, Hoole was said as living in the time of Glaux. Since Hoole was the founder of the Guardians of Ga'Hoole, and many owls existed at the time (they came into being after Glaux's time on earth), Kathryn Lasky probably hadn't Hoole to be the founder then.
- The three main Ga'Hoolian legends took a thousand years before Soren's time. Since the wolves migrated to the Beyond to escape the Ice Age then, the owls must live a thousand years after the Ice Age. But humans still existed then and since the owls lived long after humans, this also probably means they can't tell time well again.
- In The Rescue and in a preview of The Journey, Gylfie's name was incorrectly spelt as 'Glyfie'.
- In The Golden Tree, it says "Nyra held the battle claw in her teeth", but owls do not have teeth.
- In To Be a King, it is mentioned that Coryn recovered the ember from the volcano Dunmore, but in The Outcast, he retrieved the ember from Hrath'ghar.
- In a line in The Rescue, Poot is described as having ear tufts, but Boreal Owls do not have ear tufts.
- Seagulls are looked down upon by owls because they can't yarp pellets, when in fact gulls - and many other species of seabird - do regurgitate pellets.
- In The Burning, Hoke of Hock mentions that yoicks is the same in both Hoolian and Krakish, while in The Rise of a Legend, Krakish-speaking animals say "yoickers"
- In The Rise of a Legend, Lysa dies when a pine tree explodes, but in A Guide Book to the Great Tree, Ifghar mentions that she fell out of a tree and was eaten by a coyote.
- The Rise of a Legend also mentions that Lysa was born after Lyze went to learn to fight, but A Guide Book to the Great Tree says that Lyze had just begun branching.
- On page 156 of The Hatchling, Grank is described as a Whiskered Screech Owl.
- On page 110 of The River of Wind, Primrose says "I'll eat my trousers." Owls don't wear trousers, and not many owls in the series knew all that much about the life of humans (Others).
- On page 166 of The Journey, Gylfie refers to the first meal of the night as "breakfast". Otherwise, the owls of the Great Tree always call this meal tweener.
- In the movie, several owls have wrong eye colours according to the books and reality:
- Soren has golden eyes.
- Kludd, Eglantine, Noctus and Marella have amber eyes.
- Digger has green eyes.
- Nyra has blue eyes with hazel or amber around the pupils.
- Metal Beak's un-blind eye is yellow.
- Jatt and Jutt are both odd-eyed, for each one has one amber and one green eye.
- Allomere has gray eyes, but all Great Grays have yellow.
- When two Pure Ones attack Grimble to try to get to Soren and Gylfie, one is thrown onto some books and one is sprawled on the ground in front of Grimble. However, a few moments later, they both disappear.
- When Nyra takes the best new soldiers to Metal Beak, Jutt lands on the left of Jatt. However, when the camera moves away and then back, they have switched places.
- After the owlets are moon-blinked, Pete is seen walking in front of Soren. But as the camera moves to Gylfie, Pete is walking behind her.
- Even though owls cannot move their eyes in their sockets, owls in the movie are commonly seen rolling eyes (i.e. Dewlap and Soren) and glancing sideways (i.e. Twilight and Gylfie). By staying true to the owl's actual eye behavior, this would make the characters seem pretty "dead" and emotionless and would have to move their heads a LOT to have direct eye contact with whoever was being addressed. This realism would also push the movie/game into the Uncanny Valley, which would make the movie/game bomb terribly. The artists, therefore took the artistic license of making the owl's eyes moveable in their sockets for that reason.
- When the guardians and the Band fly over Hoolemere to get back to the great tree, Boron is seen carrying a snowy owlet. But as they arrive on the Island of Hoole, he is seen carrying Pete.
- Even though female owls are larger then males in real life and in the books, all females in the movie are either smaller or the same size as their mates (i.e. Nyra and Metal Beak, Marella and Noctus).
- In the movie, Twilight sings "As the night falls, so do we. We fall asleep." despite the fact that owls are nocturnal, and are awake during the night.
More coming soon