Continuity mistake: The second time Harry conjures the patronus charm to save Sirius and the other Harry from the dementors, Hermione is standing next to the tree behind him. The first time he uses it, his silhouette can be seen from the other Harry's point-of-view from across the lake, but Hermione isn't next to the same tree, even though the spot she was standing in is visible.
Picture added by Super Grover
To submit a picture, just click the edit icon under the relevant entry, then choose 'add a picture'. Thanks!
All images remain the copyright of their original owners - these low resolution images are simply individual frames used to demonstrate the entry.