3. Lazy Foreshadowing
There's a line early on in The Hobbit in which Gandalf says to Bilbo, "true courage is not about knowing when to take a life, but when to spare one", an eye-rollingly obvious piece of foreshadowing that makes it clear to even non-Tolkein fans that this will be a dilemma that Bilbo faces later on in the story. This occurs when he attempts to escape Gollum while in possession of the One Ring, and has the choice to slide his blade in Gollum's neck, but opts against it. The line is clumsily prescient, making Gandalf seem too aware of what is to come, and cluing viewers in too much on what's going to happen. Easily one of the worst pieces of signposted dialogue in recent film history, it's one of those lines that, clearly, was an original zinger from Jackson and his scribes.