When Martha is talking about the Oasis of Serenity, Castle asks 'what is that?' Martha replies 'haven't heard of the serenity?' Castle throws a knowing look at Alexis (reference to Firefly and Nathan Fillion's role as Mal)
At the storage unit Beckett says it might be empty like Al Capone's vault. In 1986 the journalist Geraldo Rivera mercilessly hyped a live broadcast special in which his team would open the "secret vault" of Al Capone, actually just a walled off area in the basement of a hotel Capone sometimes stayed at. Over thirty million people watched as the wall came down revealing an empty space, a bit of dirt and a few empty bottles.
The song playing while Castle and Beckett question the camera technician is "Move That Ass," a song written by two suspects from Lucky Stiff.
There are two types of 'dirty bomb'. The 1950s version was a conventional atomic (fision) bomb jacketed with normal cobalt 59, you got a nuclear blast and the cobalt absorbed neutrons, becoming a radioactive isotope and providing an ungodly amount of radioactive fallout which would contaminate the environment for years. The new style dirty bomb is a conventional chemical explosive surrounded by some radioactive material. The chemical explosion disperses the radioactive stuff over a limited area. The lid of the crate was lined with C4.
Stana Katic (Kate Beckett) and Adrian Pasdar (Agent Mark Fallon) have both appeared in the TV show Heroes (2006).