Despite its often-bleak tone and some conflict among the characters, the movie's overwhelming messages are about banding together to battle evil, not leaving anyone behind, redemption, and self sacrifice for the greater good. As in the Terminator movies, there's a clear caution about giving too much power to machines/technology. There's also a spiritual undertone to some parts of the movie, especially in regards to how the main characters came to be.
Several scenes of frightening machines attacking and, in several cases, killing the main character's friends. Although the battles are between ragdoll-like creatures and robots instead of humans and aren't gory, they can be quite intense and scary. There are also disturbing images of a machine being beheaded, characters having their life force sucked out of them, explosions, and other moments of intense, suspenseful peril. Dead human bodies are shown briefly, including a mother and child, and flashbacks and newsreel footage show an intense battle between people and rampaging machines. Weapons include spears and, in the flashback sequences, guns and chemical bombs.