Most of this discussion will take place in the 1st of the Terminator doumentaries (Well, they are as much documentary as Inconvenint Truth!). The idea is, according to IMDB.com:
In the Year of Darkness, 2029, the rulers of this planet devised the ultimate plan. They would reshape the Future by changing the Past. The plan required something that felt no pity. No pain. No fear. Something unstoppable. They created 'THE TERMINATOR'. The thing that won't die, in the nightmare that won't end. Your future is in his hands.
A cyborg, played with raw emotion and Shakespearean timing by our friend Ahnohld, assassin called "The Terminator" is sent back through time, from 2029 to 1984, to kill the seemingly innocent Sarah Connor-a woman whose unborn son will lead the human race to victory in a bitter future war with a race of machines. If the Terminator succeeds, mankind is doomed. Sarah's only hope is a soldier, puny human one at that, from that post-apocalyptic war, who has chased the Terminator back through time. The future of the human race depends on which one finds her first. There are some cute twists and ironic sub-plots involved here...
- The 'unborn' child who grows up to be the savior of mankind against the machine, ends up being fathered by Kyle, the human sent back to protect her so she'd have the child who would grow up to be the one who sent Kyle back to protect his Mom from ... You get it... So, this brings up the old time-travel paradox of going back in time, changing something important and, thereby, setting off a chain of events that lead to inescapable endless logic loops. KEWL! So, if Kyle is the Father, what would have happened if he didn't come back to the past? No child, at least, not THAT one. So, who sent him back to protect him?
- During the police station massacre, the fourth cop that the Terminator kills gets blasted by the shotgun, but we hear the sound of the machine gun instead.
- The original idea, which is included on the DVD, but not shown in the theaters or on the VHS version, was that TWO guys come back to protect Sarah Conner. However, Kyle's buddy materialized inside a fire escape and sorta died a horrible fire-escape kinda death. (This is disputed scientifically in the 2nd and 3rd installments by the spherical distortion thingees they come back in that replace a sphere of space-time with the future space-time; apparently annihilating the present stuff...)
- When the Terminator is stalking Kyle and Sarah in his police car, the sticker on the driver's door reads "To care and protect". When the car is later wrecked in a tunnel, the sticker has changed to "Dedicated to serve".