The police, coming upon the three bad guys tied up in front of the storage locker, say "What's all this then?" This is a standard expression used by the police in British movies/shows, and was popularized by Monty Python.
The briefly scene outside of "Claridge's" auction house is in fact the Victoria & Albert Museum in London.
In the opening airport scene, Hardison mentions Duberman's algorithm. Larry Duberman (played by Arye Gross) was the mark in The Reunion Job (2010).
When Nate is showing the statue of Ra to Keller, Keller says he thinks it came from the Bellingham Collection. This is a reference to a Richard Austin Freeman book called "The Eye of Osiris," where a man who is obsessed with collecting Egyptian antiquities, John Bellingham, and goes missing in London.
The statue of Ra later appeared in the private collection of the villain DuLaque in The Librarians (2014), which Christian Kane (Eliot Spencer) also co-starred in. Both Leverage and The Librarians were co-created by Dean Devlin.
One of the prop statues of Ra was later sold at a joint Leverage/Libraians props auction after the latter series concluded.
One of the prop statues of Ra was later sold at a joint Leverage/Libraians props auction after the latter series concluded.