In Nick Lane's flat there is a wall filled with clippings. In the midst of this mass of clippings is a sheet of paper on which the number 47 is written. The number 47, besides being a prime number, has been attributed as being a random number which occurs with unusual frequency and so has a certain mystique. There is perhaps a humorous mathematical proof of this by Pomona College's math professor Donald Bentley. Regardless of this purported mystique, the number has been used in Alias (2001), another J.J. Abrams project, as a central plot device for the series.
When the Fringe team arrives at the building in New York where Nick Lane has stationed his "hostages" around the top of the building, The Observer is seen crossing the street as they approach that building.