5. The Clean Slate MacGuffin (The Dark Knight Rises)
The Subplot: Selina Kyle initially agrees to steal Bruce Wayne's fingerprints in exchange for a copy of the Clean Slate program, which can be used to erase a person's identity from every database on the planet. Though John Daggett reneges on his promise to Kyle, Bruce gives her the program on a flash drive after returning to Gotham, allowing her to wipe herself off the map in exchange for help securing Gotham. Why It's Irritating: In case you're not aware, the term "MacGuffin" was popularised by Alfred Hitchcock in order to explain an item of some kind that initially appears important in a movie's plot, but ultimately has little bearing in the overall outcome and is typically spoken about in only vague terms. That pretty much defines the Clean Slate tool to the letter: it is largely irrelevant to the central plot beyond a few cursory moments, and given how bloated the movie already is, is completely unnecessary.