At the start Sam says " All for one and one for all". This is a famous The Three Musketeers (1993) quote in which Chris O'Donnell stared.
In the beginning scene at the office a large box is delivered which spikes Deeks curiosity. When he goes to Google the return address G, played by Chris O'Donnell, tells him it is against the law. Deeks answers back and at the end says to O'Donnell "all for one and one for all. Isn't that what you used... " where he gets cut off. This is in reference to the Disney version of The Three Musketeers (1993) that O'Donnell played in.
The large cardboard box that shows up reappears off-and-on over the next six years and eventually plays a very large part in the lives of Kensi and Deeks.