Robin Hood asked Clara Oswald what she knew of the Doctor. When he revealed what he learned from her, the Doctor said that she shouldn't have said that. The impression I received from the conversation was that the Doctor expected Clara to keep certain things said between them.
When Danny described the Doctor as being aristocratic, the Doctor didn't refute the description.
It is the centennial of the First World War. Why is this important? One of the beliefs held about this war was that brave soldiers would follow the orders of their leaders, even to their own slaughter. "Lions led by donkeys". The last season of Blackadder and Oh, What a Lovely War! popularized this notion. I wonder how much of this is filtering into Doctor Who.
http://en.wikipedia.org/wiki/Lions_led_by_donkeys
There are references to the earlier Classic Doctor Who, when the Doctor said the robot was attracted to the high level of artrons in the area of Coal Hill School. Three stories are set in and around Coal Hill School.
There are so many questions about this robot.
1.) Why was it so programmed so badly? Military personnel are trained not to shoot at a moving target; they are trained to shot at where the target will be. This robot was shooting at where the target was.
2.) The robot was controlled by an artificer. The Doctor impersonated an artificer, rather effectively. Who sent the robot to 21st century Earth? Whoever sent the robot, they had to know of the history of the Coal Hill School. (Will this be explored in a future episode?)
3.) How did the Doctor learn about the robot?
We have only the word of the Doctor that the robot was a threat to humanity. The robot's actions proved it was less of a threat.
It is implied in one of the episodes, I think the Sarah Jane series, that Ian Chesterton hasn't aged since the 1960s. So, seeing an aged Chesteron would contradict that. I am glad that there was no cameo.