I think these figures are to captivate the overactive childrens' minds not professional scientists
I think a child's imagination would be captivated far better by plausible figures, because with plausible figures you can actually imagine these feats being performed in reality.
The speed of sound is 344 m/s. Dragonite flies almost twice this. Just by doing what Dragonites do for fun, it's using Extremespeed to get Supersonic (defined as 1.2-5 times the speed of sound), which would cause quite a powerful Sonic Boom as it passes. Its bone structure would also have to be harder than the steel and titanium used in modern aircraft, because the forces exerted upon it when it turns would be
phenominal. There's no way it could travel this speed and hope to keep a passenger on its back, as well. Your arms would be torn off if you kept that good a grip on it.
For you American kids out there who don't know the metric system (and shame on you), one mile is 1609 metres. Dragonite can fly over a mile (1.18 miles for those who care) in three seconds, and can keep this speed up for 16 straight hours. That's 23.59 miles in one minute, or 1415.4 miles per hour. A drag racer can reach, at best, 530 km/h (or 330 mph), taking 4.45 seconds to cover 402 metres (a quarter mile). A Concorde jet flies at 2.02 times the speed of sound, or 694.88 metres a second, which is only 1.089 times faster than Dragonite. However, neither the drag racer nor the Concorde can maintain this velocity for very long—the Concorde can get from New York from London, but that's about as far as it goes. It isn't going to circumnavigate the globe any time soon like Dragonite can (what does this dragon
eat to give it more fuel than a supersonic jet?).
Aaaaaaand that's all the math I care to do for the moment.