Question: Why is it that the aliens, who obviously possess technology and intellect far beyond humans, didn't think to use their pictographs to communicate right out the gate? We had to wait for Amy Adams and her dry erase board?
Answer: The aliens don't see time in a linear fashion but all of time at once, meaning they can see the future, which is why their writing is like it is. They therefore knew Louise (played by Adams) would be the one to figure out their language and had to wait for her, or simply chose to wait for her.
Question: I may have missed this, but early in the film, how did Mia and Sebastian get into the empty planetarium? It must have been locked up pretty tight. Did someone let them in? Did they break in? I'm guessing this was explained and I didn't catch it.
Chosen answer: The answer is, "It's a movie." They wouldn't have been able to drive up to the entrance either. The entire sequence is fantasy-driven.
Question: Who was the 4th person killed? In the when he confronts Toby, he says "Help me understand why 4 ppl died..." To my count, there were 3 ppl killed: 1. The customer in the bank in Post 2. Ranger Parker 3. Tanner (Ben Foster). (01:33:20)
Answer: The fourth person killed was the security guard in the bank at Post. He was killed just before the bank customer.
Answer: The Heptapods' "present" encompassed about 6000 years of our human past, present and future. So, they perceived 3000 years of our past and 3000 years of our future simultaneously. It's a confounding idea to humans, but the Heptapods already knew, 3000 years in advance, that Louise was the critical contact for the evolution of communication between our species. For the Heptapods, there was no coincidence or impatience or blind luck; they already knew exactly when and how to start communicating with her.
Charles Austin Miller