Question: At the beginning of the movie, it was shown that both Tony Stark and Nebula are stuck inside Peter Quill's spaceship after Thanos' snap. Here, Tony Stark says, "Oxygen will run out tomorrow morning." However, this doesn't make any sense. Why didn't the two of them just stay on Titan? It's not like they needed special equipment in order to breathe on Titan before. They could just stay there until help arrived.
Answer: What help? Nobody knew where they were, where to start looking, or if they were even alive. Tony had a wife and daughter on Earth; he had to get back.
Question: Did it actually have to be Tony that had to snap Thanos and his army? What difference would it have made if somebody like Clint or even Peter Quill snapped them? As long as Thanos and his army were destroyed the world was safe.
Answer: Yes. It HAD to be Tony. Strange said there was only ONE timeline where they succeeded. Also, Tony's armor provided some level of protection, letting him live long enough to snap. Most others, besides Hulk, would've died just by putting the gauntlet on. But, Strange foresaw this. He SAW this one reality where our heroes win. He SAW Tony die. It's also why he pointed and nodded at Tony. There were probably other timelines where someone else got the gauntlet but couldn't survive long enough to perform a snap. Clint would've died without armor, and Peter no longer had his Celestial powers after Ego died, so Peter would've died too.
Question: At the end when Gamora and the Good Nebula are speaking, Gamora asks Nebula what happens in the future and Nebula responds that she tried to kill her many times, but they eventually became friends. Why didn't Nebula bother to tell Gamora that Thanos killed her to get the Soul Stone. Seems odd that she left that out.
Chosen answer: Nebula already alluded to Gamora being killed by Thanos earlier when she said something along the lines "You know what he does to you?" In this scene in question, Gamora is already disillusioned with Thanos and frees Nebula from captivity to battle him, thus it's not necessary to show the audience Nebula telling Gamora what Thanos did to her. She may have told her offscreen while they were on their way to find the evil Nebula.
Question: In the final fight scene, why were the Avengers trying to get the gauntlet to the van? What were they planning to do with it?
Answer: The van had a quantum tunnel which they could use to get the gauntlet away from Thanos forever. It was a last ditch effort to prevent Thanos from obtaining it.
Question: The beginning of the film shows that Clint is still on house arrest. Ant-Man and the Wasp showed that Scott's house arrest ended well before the Snap. Aside from being sentenced at a later time than Scott, is there any reason why Clint would be given a longer house arrest than Scott? Wouldn't his time working for S.H.I.E.L.D. make it more likely that he would have got a more lenient sentence?
Answer: Nothing was said about what Clint's sentence was, but we do know Scott took a plea bargain and therefore may have got a lighter sentence. And the fact that Clint worked with S.H.I.E.L.D. might have given him a longer sentence since he should have known the importance of following the Sokovia Accords. The out-of-universe answer is because the writers needed to show why Clint wasn't in Infinity Wars.
Answer: If they have no way of communicating with anyone, they have no chance on Titan either. That planet is dead too—might actually be hazardous to stay there too long. Nobody knows they are there either. They took their chance with the ship and getting to Earth.
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