Trailers pull this dirty trick entirely too often. When the internet-breaking teaser for Avengers: Age Of Ultron debuted, the most shocking part wasn't the dramatic Pinocchio cover; it was a shot of someone's (Thor's?) body lying next to Captain America's broken shield. That's the ultimate "s**t's getting real" sign in the Marvel Universe.
After "Spider-Man shutting up for one second."
Cap's shield is supposed to be unbreakable -- without that feature, it's nothing but a very heavy Frisbee -- so this was a huge deal. They even used the broken shield as part of the marketing campaign, so you knew it was an important part of the movie and not, say, a magical fever dream Tony Stark has. Wait, no, that's exactly what it was. It's an illusion created by Scarlet Witch. The shield doesn't so much as get scratched during the real story.
There's also the epic vampire showdown in the The Twilight Saga: Breaking Dawn -- Part 2 trailer (magic vision) and the Luke and R2-D2 moment in the Force Awakens trailer (Force vision). And then there were all those post-apocalyptic shots that made up, like, 5 percent of every Batman v. Superman trailer:
Whoops, sorry, this is from the superhero-themed Fifty Shades Of Grey porn parody.