Warning: Below are SPOILERS for Avengers: Infinity War !
Russo Brothers went extremely far to prevent leaks and spoilers for the biggest movie in the biggest film franchise yet Avengers: Infinity War . This was especially important for the devastating end of the film, so that the audience could be left untouched and flattened when they saw it. To ensure the secrecy of the end, even the cast was not exactly told what it was before the time. Instead, the actors were told the end of the movie just before they shot in a van, as the Scarlet Witch herself, Elizabeth Olsen, explained:
That must be a strange experience, as one tells the end of the film stuffed in one Van with all your co-stars, minutes before you have to film your death scenes. It also seems like it's difficult to be an acting challenge to find that your character turns to dust and has to figure out how to interpret that with your performance. What Elizabeth Olsen described at ACE Comic-Con (via MovieWeb) must have been pretty visual as well. Think about it: All the heroes of the MCU packed like sardines in a van and listened attentively, while the Russo Brothers explained what the end is. It's almost silly, but these are the steps necessary to prevent movie leakages in the Internet age. Heck, they probably swept the transporter for bugs first too.
The Infinity War performers were allowed to prematurely read the full script if they wanted, but to do so they had to leave their cell phones in a windowless room and they could not take a copy home to cover their lines memorize. The actors and actresses took parts of the script, but these pieces had wrong scenes and ends, just in case they fell into the wrong hands. So while the cast knew the broad strokes in advance, it sounded as if what was going on at the end of the movie was not clear until the Russo Brothers interpreted it and explained what was happening to their characters As soon as Thanos started his fingers.
Not all performers were left in the dark about the fate of their character in Infinity War . Loki actor Tom Hiddleston also revealed to ACE Comic-Con (via comicbook.com) that he actually found out that his character had no more tricks before stings Thor: Ragnarok as he declared, and reached his end:
I guess, given how little Loki is in the movie, it was probably hard to tell him his role in the movie without revealing his death. His tragic fate has indeed influenced how Tom Hiddleston played the character in Ragnarok and knowing what would come he could help Loki become an "Odinson" again before he came to an end.
Marvel Secrecy Machine rolls on as we embark on the next year Avengers 4 . This final film of Phase 3 not only brings with it the question of who will die but also who will resurrect to fight again and what the MCU will look like when it enters Phase 4. If the cast in a hot room was crammed with Van to learn the end of Infinity War I can not imagine what they must have gone through to see the conclusion of this next chapter.