Specifically, the reddish shape near the middle of the face of Earth is Australia, according to a NASA press release. If you think the moon looks a bit too close to Earth in the image, NASA explains the observation and subsequent composition were made based on when the moon was almost directly behind the Earth from Mars' point of view, and that both objects are actually in their correct positions relative to each other.
Again, it's worth noting the images weren't captured from the surface of Mars, but rather a high-tech camera on NASA's spacecraft orbiting the red planet. It's probably safe to assume Earth would look more like a blue-tinted star if you were standing, say, right next to the Curiosity rover. If Elon Musk has his way, though, we might just see it for ourselves someday.