Two things that I’ve found myself wondering about:
First, who is the father of the Rhinemaidens, the one who entrusted them with the Rhinegold, told them how it could be fashioned into a ring of power, and warned them about “such a foe” as Alberich? I guess in the back of my head I’d thought it must be Wotan, but I realized last week watching the opera that this can’t be right. When Loge mentions the gold, Wotan says of it “hört ich raunen” (“I have heard whispers”), which would be a pretty odd thing to say if he’d given it to them. Probably more decisively still, he then has to ask Loge how one could go about making the ring, which pretty much scotches any notion that he was the one who told the Rhinemaidens how to do it.
Second: What, exactly, does the ring do? We see Alberich use it to summon the Nibelungs at one point, and it apparently enables him to make the Tarnhelm, but its powers are left pretty vague. Notable, though, are the things it doesn’t do. It doesn’t allow Alberich to do much of anything to free himself when Wotan and Loge capture him and truss him up. It doesn’t prevent Fasolt from getting a club to the head, which is understandable enough, since he’d just barely picked it up and presumably had no idea how to use it. But neither does it prevent Fafner from succumbing to a stab wound. Brunnhilde seems to threaten to use it when Siegfried (memory erased by a potion) comes to abduct her in the guise of Gunter, warning him that it makes her “stronger than steel,” in response to which he unceremoniously rips it from her finger. Some ring of power.