One of the things KSP taught me is that orbital mechanics aren't that complicated, but even so, pretty much all movies and TV shows about space were written by someone who doesn't even know the basics.
Expanse season 1 was a nice exception to the rule, but I find that as the longer the show goes on the more it gets ignored. Missiles that fly into the sun at faster than light speeds...
The expanse still gets the physics right for the important scenes. Watching people stand for over a few days looking at a torpedo slamming into the sun would be boring.
That sequence was indeed not realistic. It's interesting to keep in mind that according to Expanse-lore, the Epstein drive on human-rated vessels operates typically around 11G. It is likely that a missle that is much lighter, so the rocket equation has less teeth, and not constrained by fragile meat-bag-physics, would be even more powerfull.
But if we just assume 11G, and constant acceleration (remember, specific impulse is supposed to be 1,100,000 seconds), that gets you to 0.05c in 37 hours. At that point, 8 lightminutes (1 AU) takes for example 160 minutes to travel. Not instantanious by any means, but a lot faster than one would imagine.
I’d argue that it’s just an effect of lazy writing though. Deorbiting anything into the sun is a very expensive way to get rid of it. They showed instant proto molecule cleanup operations in another season - just use that again.
The vanilla KSP physics aren't realistic, only the nearest/most influential body exerts gravity on the spaceship. With the Principia mod[0], more realistic and complex maneuvers[1] can be simulated.
"Orbit Type Diagrams"[3][4] show the fractal-like complexity of three or n-body problems[5][6]
KSP physics may not be realistic, but they should be close enough for most movies and TV shows, yet they don't even approach that. I think that's the point of the parent.
The problem is that if you show a ship heading away from a planet by burning parallel to it, or heading to the planet in the same way, people watching will be confused.
Often, artistic license take over actual physics, even when the writer knows about the field, he will prefer do it in a way that fits the plot.
I mean, even Interstellar, with a Nobel Prize on board sometimes forgoes scientific accuracy for nicer pictures.
There is also a game about accuracy, viewer expectations, and attention. For example, most people will thing that the best way to land from orbit is to point the ship towards the ground is fire the thrusters, obvious right. If the ship points 90 degrees away, people will ask themselves why. If orbital mechanics is central to your movie, that's good, but you may have some explaining to do. If you are in the middle of an epic space battle, it is not the time for a physics lesson, so go for the obvious (and wrong) and let the viewer focus on the action.
They are still making a work of fiction and entertainment, so some shortcuts are taken. Series like Star Trek just come up with new physics and word salad to progress the plot and pull out their deus ex machina.