12. Guardians of the Galaxy — the sphere scene
According to the director, Chris Pratt dropped the sphere with the Stone of Infinity not because it was planned but because he was just clumsy. He dropped the sphere, but he stayed in character. That’s why this mistake looks like it was originally in the script.
11. Avengers — the blueberries
Robert Downey Jr. got into his character so well that he “gave” him his own habits, including having snacks all the time. The scene with him offering blueberries to Hulk and Captain America was just an improvisation.
10. The Princess Diaries — the fall
This moment was not originally planned, but the sudden falling of Anne Hathaway was so appropriate to the clumsy princess Mia’s behaviour that it was decided to leave this scene in the movie.
9. The Lord of the Rings: The Fellowship of the Ring — knife throwing
This scene could have ended tragically if it was not for a lightspeed reaction of Viggo Mortensen. A knife that was aggressively thrown by the orc actor slipped and was heading directly for Viggo’s face. He managed to strike it aside with a sword so that it just broke into splinters. It seems like Viggo’s weapon training was not in vain, and the movie acquired one more dramatic moment.