While trying to find Siegfried in the hotel, Max tells 99 about the "Oppenheimer Case"...a nod to writer/director Jess Oppenheimer.
Show producer Burt Nodella appears as the KAOS doctor. He chose to be credited as "Cary Nodella" in honor of his daughter, Cary.
Title is nod to popular British WWII movie "One of our Aircraft is Missing".
In order to find a double agent, 86 has to use the password 'Pussycat, pussycat where have you been'. To which the right man will answer 'I've been to London to visit the Queen'.