The Final Flight of the Osiris was originally shown as a standalone piece in the theatrical release of the Matrix Reloaded preceding the main film. This helped provide background information as to how the humans first found out about the machine threat to Zion.
In The Second Renaissance Part 1, the robot who first rebelled against humans is designated as "BI-66ER," a reference to Bigger Thomas, the protagonist of the 1939 novel Native Son, giving the rise of the machines a backdrop in historical race relations. In the novel, Thomas is a black teenager who comes from a poor, working-class upbringing and goes to work as a butler for an affluent white family until he accidentally murders his employers' daughter and ultimately receives a life sentence for his crimes.
WILHELM SCREAM: in the episode, "Matriculated". It happens when the Sentinels attack the humans in the lab near the end.
There is a reference to the Visual Effects Supervisor for the Matrix films, John Gaeta, during "The Second Renaissance Part II." As the human army gathers in the trenches, preparing for Operation Dark Storm, a male voice on the P.A. system announces, "Lt. Gaeta, please report to the Ops Center. Lt. Gaeta to Ops Center."