Driving across the Nevada emptiness recently, listening again to Jim Dale's excellent CD recording of Harry Potter and the Deathly Hallows, the other DrC and I identified a Harry Potter anomaly, that is, a place where reality in one book changes or is different in another volume. The example we put before you today deals with the secret passage which runs from under the Whomping Willow on the Hogwarts grounds to the Shrieking Shack on the edge of Hogsmead.
In book 3, Harry Potter and the Prisoner of Azkaban, that tunnel is tall enough for three adult wizards - Lupin, Pettigrew and Black - to walk in side by side chained together. The ceiling is low enough that a stunned, levitated Snape bumps his head but apparently nobody else does.
In book 7, Harry Potter and the Deathly Hallows, Ron, Hermione, and Harry discover that they now have to crawl to traverse that tunnel. None of the three remarks on this change so we cannot attribute it to a magical shrinking of the tunnel, instead it is implicitly attributed to their growth over the four years from age 13 to age 17. However, it is unlikely that they have grown so tall that they dwarf Lupin and Black.
It appears that a continuity editor missed this anomaly.
