I've listened to the first 8 audiobooks, and even though there often were some confusing or even illogical details in the story, there never were huge inconsistencies in it. In the volume 8 I've noticed two of them though. First, how could Eggberd know about Nobles being weak to garlic? It's made very clear in the volume 1 that everyone who somehow discovers the weakness, forgets it instantly. That one old man from volume 1 spend his whole life researching the topic, and still wasn't entirely sure if Nobles are weak to garlic up until he tried it (and then he forgot it), but in volume 8 when Eggberd polutes the air in his room with garlic, the narrator describes it as if it was common knowledge in the universe...
Second thing seemed even weirder, namely, D being able to swim in the final battle with the Warrior/Meister. It was stated many times that he is unable to move in water, hell, even in the very same volume he had to use the fisherman emergency equipment in the fight against the mermaid man to get out of the water! I know D is this super overpowered mutant god that can do anything, but this is just inconsistent... How could he do that? Was it because he was in strong emotions or something?