I don't see how those creature could possibly get that much weight off the ground to fly. And Ghidorah even lifts Godzilla off the ground. Seems absolutely impossible.
shareSure, as long as they were strong enough or had some form of anti-gravity.
shareGhidorah seems like it couldn't fly, but Rodan is not very different from an Archaeopteryx or a Pterodactyl, both of which could fly.
shareHaven't seen this movie yet, but, yes, it is impossible for giant monsters like this to fly.
Laws of physics state that doubling the size of anything -- making it twice as big in all dimensions -- increases the weight of it by eight. Mechanical considerations mean that muscles wouldn't be able to take the load.
Giant ants, spiders, etc would collapse under their weight if they were monster sized. So all those 50s era giant bug movies -- as goofy fun as they were -- are totally unrealistic.
Pterodactyls had about a four foot wingspan. Rodan -- according to Google -- has a wingspan of 871 feet. Meaning, he'd not only not be able to fly, he'd probably wouldn't even be able to stand or even draw a breath.
Interesting article here about the upper limits of dimensions to be able to fly.
http://www.nbcnews.com/id/49746642/ns/technology_and_science-science/t/pterodactyl-was-so-big-it-couldnt-fly-scientist-claims/#.XZDtpkZKjIU