What’s she marvelling at? I’m sure Comic-Con crowds are a sight to behold, and Bettany’s sunglasses look impressively retro in the photographs. But I don’t think that’s what the Daily Mail means here. I think there’s something more ambitious going on.
“Marvel”, the verb, is frequently followed by “at”, and there is an “at” in this headline. But it’s not right up against the verb, where you would expect it. The preposition that immediately follows the verb is “in”, introducing a phrase that relates to the dress. So Elizabeth Olsen, I think, is not supposed to be “marvelling … at” the venue or her colleague, or indeed anything else. She’s “marvelling” in a way that celebrities featured in the Mail have previously been known to “stun”, “wow”, “dazzle”, “electrify”, “shimmer” and “amaze”. She’s looking marvellous.
This type of construction is familiar to tabloid readers: most of the time, they seem to be what you might call “implied object” headlines, since the star in question is usually stunning, wowing or electrifying somebody else – fans, media, the crowd – not explicitly mentioned. Such headlines reek of journalese, but are easily understood if the verbs are transitive (“electrify”, “amaze”) and clearly propose the idea of a second party. They also work with what are sometimes called “unaccusative” verbs, like “shimmer”, that describe an involuntary state of the subject.
But “marvel” is the kind of intransitive verb that usually demands either an indirect object (“they marvelled at the moon”) or an entire clause as a direct object (“they marvelled to see the moon“). It can stand on its own (“They marvelled.”), but in a sentence containing unrelated prepositional phrases, the risk of misunderstanding is high.
Obviously, as a sub-editor, I find Marvel Comics puns as hard to pass over as anyone else. But I don’t think Grammar Hulk’s going to like this one.