In Guardians of the Galaxy, Star-Lord reads a letter from his mother. But if you watch carefully, you'll notice that the voice-over narration doesn't match the words on the paper.
This is 1 of 20 movie bloopers that made it past all the editors and into the final cut. This video by Looper also shows blunders in Braveheart, The Shining, Back to the Future 3, and The Dark Knight Rises.
-via Gizmodo