My recollection is that, in the Prisoner of Azkaban movie, Harry, Hermione, and Ron see Buckbeak being executed, before
travelling back in time to prevent it.
However, this didn't happen in the book, and the idea that they saw something that was later changed to never have happened is inconsistent with other scenes, e.g., Hermione being hit by a stone that it turns out was thrown by her future self, or the whole business with the Patronus.
So did Harry, Hermione, and Ron really see Buckbeak executed in the movie? If so, how can that scene be reconciled with the other ones?