Question: This has been a question that's always brought up. Was Ellie Grimbridge always a robot from the very beginning, or was she turned into (or exchanged with) one when she was held captive at the shamrock factory?
Answer: Another theory might be that Ellie has always been a robot but an advanced model that Cochrane designed to interact with the outside world.
Question: This is a two-parter: 1) Why was the guy killing all of the kids, and 2) How exactly did he do it?
Answer: He was trying to perform a human sacrifice. He mentioned to the doctor when he was tied up that three thousand years ago, there was a massive sacrifice where the world flowed with the blood of children and animals. Now the planets were aligned again and it was time for a new one in order for the people of his craft to control their environment.
Answer: Because he was an evil mastermind. He implanted lethal microchips in the tags of Silver Shamrock masks so when the commercial aired on T.V. on Halloween night, it would take a deadly effect on the kids wearing the masks while watching the commercial.
Question: I could be wrong, but wouldn't destroying the Silver Shemrock factory disable the commercial and/or the mask chips?
Chosen answer: They don't broadcast the commercial, the cable company does. And the mask chips all have tiny pieces of the rock inside, so they will still work regardless of whether or not the factory is destroyed. So the answer is "no" and "no."
Question: Why did the town of Santa Mira have a curfew?
Answer: Because that's when Conal Cochran and his minions do their 'work'.
Question: Cochran's plan hinges on kids still having the Trademark tags on their mask, and for some strange reason they keep those tags on. Marge even said they trademarks shouldn't come off easily. Why? You'd figure the first thing you and your kid would do after buying a mask is to remove the tags, so they don't rub against your skin.
Answer: It is not a hanging price tag like you would typically find on a rubber Halloween mask. It looks more like a large silver button that is attached to the mask itself. Removing the button would leave a large hole in the back of the mask which would not be desirable. It also appears that the button has a front and back, meaning it was put onto the mask in two pieces. Presumably Marge is saying it would be very difficult to remove the buttons by trying to "open" them. The one child in the test run we see wearing the mask, albeit briefly, doesn't appear to be uncomfortable. That is until snakes and insects burst out of his head.
Question: How exactly did Cochran manage to smuggle that massive Stonehenge all the way from England to California?
Answer: He wouldn't have to smuggle it, lots of things are bought in foreign countries and shipped to America. London Bridge in Arizona or put on display in buildings and parks.
Except the news report flat out said the stone had vanished and everyone was freaking out about the theft. It was not obtained by legal means. We're never told how they managed to get it; probably in some supernatural manner.
Chosen answer: She was turned into one when she was captured. The robots didn't speak and if you notice that after he finds her, she never says a word. As well, she displayed genuine emotion throughout the film before she was captured, something the robots also never did.
I agree, she was a real person until she was captured. If she were a robot, I think Chalice would have found that out when they made love. Plus, as you mention, she had real emotions until her robot replacement was rescued.