The conversation in this chapter between the three was understandably cut short for manga adaptation. Not much was really left out, but I thought I'd mention one innocuous thing that Alka said in the novel version that stuck with me.
Alka says something to the effect of research having been done on dungeons with destroyed cores, where intelligent dungeon monsters don't die along with the dungeon. She's says this to try to convince Uuma to stand aside and let the dungeon core be smashed.
So say Rokuko (and Keima) died, the rest of the cast might not. It obviously also implies she's aware of intelligent dungeon monsters, hence why she's not that surprised by Uuma.
Just a bit of curiosity. I don't think it's a spoiler to say so since it's just omitted in the manga, but to my knowledge this never materially comes up again.
There was one other thing omitted which I thought was significant, but I'll keep mum on that for now, maybe it's been moved to the next chapter.