Hmm. There are a few flashbacks to Odin just after he lost his eye, but it's not done in a graphic/gory way, just him with blood on his face. Several people get frozen over, because well, frost giants. There's a lot of battle, but wounds are glossed over, except one demonic creature (dinosaur-like) who gets a hole in its head, but no gore to go with it. The most common thing is for people to get knocked into things, really - very much cartoon violence.

One trigger could be medical settings. Thor lands on Earth (in the first scene ;)) and doesn't take well to a hospital, so he's subdued with tranquilisers and later tied to a bed. All done without graphicness, but I see where it could make a person with mental issues shiver - maybe alert her to it and assure her that he escapes shortly?