When they examine the robot in the morning (after the kid dragged it out of the mud) Bailey makes the comment that it is unlike anything she has ever seen before. (The next day she suddenly declares him to be a sparring robot).
When Max is out playing with Atom he has the robot lift him up and he asked the robot if he can understand him. He then tells the robot he will keep his secret.
Later in the movie before a fight Max is working on Atom in the staging room. Max and Charlie are invited to the box office. When they leave Atom is left and he turns and looks at himself in the mirror.
Was Atom more than just a simple sparring robot?