Traffic Jam
We see a heavy flow of traffic on the Los Angeles freeways in the opening scene. Then, we see cars burnt out by a bomb along with a skull of a human being in the car. This is a symbol that the machines have taken over, that Judgement Day is upon the people as Skynet has unleashed itself upon the earth.
Father Figure
We watch as John begs and order The Terminator not to sacrifice himself at the end of the film. The young boy cries as he does so. This is a symbol of his affection for the machine, which has been his protector and has essentially become a father-figure to him.
T1000
The T1000 is an upgraded Terminator sent back to kill John Connor, the young boy who becomes the leader of humanity against the machines in the war at Judgement Day. The T1000 is a symbol of the machines relentless pursuit of victory through upgraded technology, but it is also a symbol that they have yet to win the war. If they had, they wouldn't need to send a Terminator back at all.
Terminator
The T-800 returns to protect John Connor, Sarah's son from the T-1000. The very fact that the the original Terminator is John's protector is a symbol that man and machine are beginning to work together (albeit in a way that the Terminator was reprogrammed). This symbolizes man's ability to fight the machines in the future and there is still hope.
Skynet
Skynet is the system that was built in order to advance technology and protect the earth. It is also what becomes the source of the war on humanity by the machines. It is a symbol of man's fallibility in our attempt to make the world a better place.
