There seems to be a mistake in Professor Layton and the Diabolical Box. It is believed that Nigel was one of the few real people in Folsense. However, when the castle collapsed, he was nowhere to be seen. But in the last image in the credits, he is seen as an old man talking to Anton. It is possible that Nigel was really in Dropstone growing old, and that the Nigel at the castle was yet another hallucination.