The establishing shot of the Agency's headquarters building zooms in on 3 tall, narrow windows recessed into a brick wall. We then cut to an interior view - of several wide, continuous windows without any recesses. They don't match the exterior windows at all.
A number of in-joke Dr. Who references crop up throughout the series pilot. A group of doctors and scientists are introduced as Hartnell, Troughton, and Baker; there's a business card for I. M. Foreman in Totters Lane; and the cover of a science magazine sports headlines such as "Time and Relative Dimension in Space" and "Playing the Game of Rassilon."