Harry Potter and the Prisoner of Azkaban - Time Travel Inconsistency
Near the end of this movie is a scene where Harry is fighting Dementors. Across the lake, he sees himself (who had gone back in time) conjure up the stag Patronus. While watching this the first time (from Harry & Sirius' side of the lake), the waves of the Patronus enter back into the "future" Harry's wand, the "future" Harry stands there for a second, and then the "present" Harry collapses.
The second time this scene is shown, from Harry & Hermoine's side of the lake, the "past" Harry collapses as the waves of light are entering back to the wand, and immediately after they disappear, Harry turns back to Hermoine, instead of standing there with the tip of the wand glowing, as it showed in the first time.