Christ that plot point was so fucking retarded too, like the kid had literally helped save the entire kingdom "oh but that's not enough to be a knight" River was just joking about all that. And then later in the season you see the actual knights and squires who all act like arrogant jackasses to Marco, and no one ever raises the simple question of where the fuck they were during that whole goddamn invasion thing Marco had to bail the whole kingdom out of. And on top of all that the knights don't even get personalities or much to do, they're just there occasionally to exposit or be in the background.
Really the whole series should be awesome with a magical realm realm of knights, monsters and royalty, multiple kingdoms all throughout the land with a race of monsters that can be credible villains with a somewhat complex history of relations between them. On top of which you also have the sci-fi element of different dimensions accessible by magical scissors only granted to either those who earn them fairly or great leaders of said dimensions. This opens the door for insanely imaginative worlds and peoples with unlimited possibilities of what kind of stories you could tell, anything from sword and sorcery barbarian tales, to hightech futuristic fiction to more mundane stories on earth if they really wanted to.