Question: Mike and Sulley are able to activate the door when stuck at the kids camp by harnessing enough screams to activate it. If laughter is 10 times more powerful than screams, then why wouldn't child laughter (especially if there is a Birthday party, etc.) not activate doors from the "human world" allowing kids to go into the factory (monster world) all the time?
Answer: Well a door first needs to be activated from the monster side. See the doors of the human world lack the receiver for the energy they need to open the doorway between worlds (the red light on top). That's why in the monster world they hook a door up to a machine to activate it allowing the passage between worlds before any scream or laugh is made. It costs power to activate a door to allow a monster in. Boo was able to activate doors because she was in the monster world and her screams and laughs triggered the devices on top of the doors, activating them automatically. This was the first time ever a human entered the monster world.
Question: Loki (as Odin) quotes a conversation that occurred between Thor and Odin. This conversation happened after Loki let go of the handle Thor offered to keep him from falling off the bi-frost. How does Loki know what Odin tells Thor when he's supposedly headed to Midgard (Earth) as they speak? Can Loki read minds? If so, I don't recall any movies he comes out in mentioning mind reading.
Answer: Loki has been shown to exhibit numerous powers in the movies that can explain how he knew about this conversation. In all the movies, he has been shown to appear in hologram-like forms in different locations. For example, in The Avengers, he uses this power to meet up with The Other who is in the middle of space, whilst he is on Earth. In the end credits scene for Thor, he was able to watch over Selvig and Nick Fury's conversation despite not being there. In Thor: Ragnarok, he was able to see into Valkyrie's past through touching her head (though this power was not established until Thor: Ragnarok). Any of these powers could have been used to find out about this conversation between Thor and Odin.
Question: How is it possible that picture 25 was in Walter's wallet the whole time, when the picture is of him later in the movie after he had received the wallet?
Answer: The picture was not taken afterwards - that spot is just a favorite Mitty likes to use to review pictures. That is why Sean O'Connell was quizzing Mitty's mum about his life/work habits, so he could take a picture of his friend for the last issue.
Question: How could Superman kill Zod by breaking his neck? He's from Krypton like Superman so he should also be invulnerable.
Answer: Kryptonians aren't invulnerable. It just takes a lot to hurt one after he has been charged by our yellow sun. There are several beings who are strong enough to break a Kryptonian's bones. Doomsday, Darkseid, etc. Since both are roughly equal in strength on Earth, its no different than one human breaking another's neck.
Question: Why on earth does Bilbo remove the ring in front of Smaug? He has no real reason to believe that Smaug won't simply eat him or roast him. Smaug can hear and smell him but can't see him, so as long as he remains still, he is safe unless Smaug gets lucky. Seems like taking the ring off is a huge risk that was not necessary.
Chosen answer: Bilbo is actually quite clever, I think he was trying to talk his way out by buttering Smaug up. If he tried to run, Smaug, who was on high alert, would have caught him and swallowed him without a second thought. By playing with words he was able to both interest and distract Smaug, and get away.
Answer: Smaug started talking about the ring, which started drawing the attention of the Necromancer (Sauron), causing Bilbo pain. Remember, wearing the ring made one noticeable to dark forces.
Question: What I don't get is that if Thalia's tree had the barrier active all along while Luke, Annabeth, and Grover were kids, in the first film, how was the minotaur able to approach close to the entrance of the camp without being prevented?
Answer: Because the barrier prevents the monsters from entering the camp, not from getting close to it. It's the reason why after Percy used the fleece to strengthen the barrier, Luke and Kronos' army used the labyrinth to bypass it.
Question: I can't figure out the ending. After Ig kills Lee and turns to stone, it is implied that he and Merrin are reunited in the afterlife, but all we see is the opening scene of the movie. Is that the afterlife? If so, why would they say that they will love each other for the rest of their lives when they are dead?
Answer: Iggy as the narrator says he doesn't know if this is paradise. It seems he's reliving his fondest memory of when they were together. I got the sense it was his last thoughts before he died.
Answer: Flash couldn't travel through time later in the movie not because Zoom was alive but because Zoom was also tapping into the Speed Force, preventing Flash from gathering enough of the Speed Force to break the Time Barrier. When Flash originally went back in time it's likely because Zoom was in custody, therefore not tapping into the Speed Force at that time.