Laurence Fishburne signed up for new sci-fi movie ‘Slingshot’ because he was “surprised” by the movie’s “twist”. ‘The Matrix’ star plays an astronaut on a mission to Saturn’s moon Titan opposite Casey Affleck in the film from director Mikael Hafstrom and he’s revealed he agreed to the project after being blown away by the script. He told The Hollywood Reporter: “With ‘Slingshot’, I was just really intrigued by the story and very surprised at the twist and the way that everything resolves itself – or doesn’t resolve itself, depending upon your point of view. “It was written in such a way that I…