In several episodes, there is a reference to Cervantes and his book Don Quixote. In this book, a delusional knight fights his own hallucinations and tries to save the world, much like Owen who thinks he's the chosen one.
At the end of credits in every episode, you can hear Owen saying, "Annie, I'm a hawk!"
The NPB logo within the show, as well as the Maniac title logo, are based on the design of the IBM logo (with all letters made out of horizontal lines).
Mobile / Smart phones never appear in the series. All phone calls are made by using landlines