Misdirection: This is a general term for any technique that leads the reader down a false path, often used in mysteries and thrillers.
Red herring: This refers to a specific piece of information or clue that is designed to distract the reader from the true solution or the real story.
Foreshadowing: This is a technique where the author subtly hints at future events or reveals information in a way that leads the reader to expect a certain outcome, only to then subvert those expectations.
Twist ending: This is a type of plot device where the ending of a story is drastically different from what the reader expects. This often involves a sudden revelation of information that changes the entire story.
Unreliable narrator: A narrator who cannot be trusted to give a truthful or accurate account of events. This could be intentional, as in a story about a character with mental instability, or unintentional, such as in a story told from the perspective of a child.
Fake-out: This is a term used in media to describe a moment where something appears to happen, but then is revealed to be something else entirely.
The specific term that best describes the situation will depend on the context and the author's intention.