The sight of Thor flying through the air has become a fairly iconic one, but did you know that the God of Thunder can't actually fly? In fact, there's a very good reason he holds Mjolnir out in front of him when he's in the sky; he's using the magical hammer to get about! When he wants to hover in the air, Thor has to twirl Mjolnir like a helicopter blade (which must be exhausting). The movies have so far avoided having him taking flight too often, perhaps to avoid trying to convincingly portray that particular visual in live-action. What they have effectively shown though is that Mjolnir actually propels him rather than allowing him to fly.
