When Mickey pulls the plugs on the computers, the children are all wearing headphones, and when he turns around and tells them to run, all of a sudden their headphones are all off.
As the Doctor and Rose are walking to the table in the cafeteria, they pass a boy sitting at a table eating lunch. He doesn't actually eat the chip in his hand, he just mimes putting it in his mouth and taking it out.
Sarah Jane Smith tells the Doctor she thought he was dead. Later she tells him she thought he was involved with the spaceship last Christmas.