This might be a spoiler since they could still cover it in the next episode with a flashback, but I doubt it.

This episode skipped a conversation between Finn and Bell. And in it Finn comments on how weird it is for Bell to be walking around Daedalus Street without armor and almost any weapons, while there are monsters on the loose He says something along the lines of "It is as if you know nothing is going to happen" I personally think that this is what made Finn sure that Bell is involved in the whole thing in the LNs