Although 'Aquaman' is a CGI-heavy blockbuster and there was likely no need to actually know how to throw a trident, Jason Momoa's the kind of actor who commits.
Case in point, he actually knows how to throw a trident and demonstrated said knowledge on 'The Tonight Show Starring Jimmy Fallon'. To be fair, most of these games / bits are usually just a bit of fun, and often a way for the audience to take in an actor doing something silly.
Not Jason Momoa. The man doesn't know or respect silly. And going by his trident-throwing skills, he doesn't do anything by half measure.
Take a look.
It should be noted, however, that Jason Momoa has some skill in the area of throwing shit. A viral video did the rounds a couple of years ago and showed the actor hurling an axe at the wall like it was nothing. Obviously, it's the same skill here - throwing stuff at a wall and making sure there's enough force to make it stick.
Jimmy Fallon, meanwhile, has no chops in the area of throwing stuff at a wall very fast and very hard - and that's OK. It's not exactly what you'd call a marketable skill and not the kind of thing you'd expect late-night hosts to have in the bag.
Nobody thought David Letterman could hurl an axe throw a wall either, like.