I don’t know about anyone else, but i find it really annoying when we get trailers from games and movies but that part is never in them.
for example, one of the game play trailers of Halo 4 had the MC kill a knight, grab its weapon and have a conversation with Cortana about what it was.
In the actual game we didn’t get that, but the MC knows exactly how to use the Prome weapons, they dont have to be scanned or any thing by cortana, I found that really annoying.
I can understand knowing covie weapons because the UNSC had been at war with them for … 7? 10? years so they have already dissected them to some degree or another.
but this is the first encounter for said weapons, how does he know how to use it, is he hiding the manual somewhere? didn’t see one in his pockets 
there was also the one where the MC appears to be captured and a knight was … staring him down?
seeing that one i got really excited to see how the MC got into and out of that one, but again it wasn’t in the game T_T
I see this time and time again and it leave me kind of disappointed because
1: we don’t get to see how that could have been part of the story
2: that hard work of awesomeness is only used for a short commercial
and 3: it can be one of the main things that gets you interested in the game/movie
it just feels like there is so much that could have been but wasn’t there.