Q:

So, what did happen on that drunken night anyway?

So, I have "A Night to Remember" as one of my (very many) open side-quests as I'm idly exploring some random wooded area I happened upon...

 Then, I come across Witchmist Grove, where I find a Hagraven.  Strange thing about this Hagraven is that she was actually named (Moira, I think) and didn't immediately go aggro on me.

 After her first lines, my prompt gives an option to ask her about a ring I (the player) currently have no remembrance of.  She declines to hand it over, seemingly jealous of some other Hagraven I've also not heard of, and then starts to attack me.

 After I defeat her and loot the corpse, I now have a wedding ring which must have been the subject of our debacle.

As if the encounter wasn't odd enough so far...

 Suddenly, I get two quest objectives immediately completed:

 - Ask about Sam and the staff in Rorikstead.
 - Take the wedding ring.

Prior to this point, I knew I had the former objective to complete, but hadn't gotten around to it.  Presumably, the former would have lead to knowledge of the latter so now I really feel like I've missed out on something.
Could someone fill in the gaps for me?
P.S.:  In probably unrelated news, I'm now fighting a dragon not far from where this all happened.  I'm sure that's not an uncommon occurrence, except this one seems strangely adept at flying backwards!

A:

After accepting to participate in a drinking contest with Sam Guevenne, you would have blacked out and woken in the Temple of Dibella. There you would been instructed to clean up the mess you made before the priestess is willing to tell you where Sam is, who presumably has the staff you won from him in the contest. 
Upon completing this small task, she will hint that you should investigate Rorikstead, and after completing the task you encounter there, you will be directed to another NPC in Whiterun, who gives you another task for which you will need the ring. As far as I can tell, you haven't broken the storyline, but have conveniently found an item you will need later.
Specifically, what would have happened between what you've done and where the quest was updated to is (SPOILERS):

 In Rorikstead, you would have been confronted by an irate farmer who demands you fetch a goat you sold to a giant while drunk. You can bypass this through persuasion or comply with his demands. In return, he mentions you were muttering something about getting married and Whiterun. Travelling to Whiterun, you'll speak to a merchant who asks you about money you owe her for a wedding ring she sold you the previous night. You have the option to seek out the wedding ring and return it -- travelling to where you expect to find your bride-to-be, you find the hagraven, which is where you accidentally came in to the story...

The dragon-flying-backwards bug was introduced by the 1.2 patch, and was hopefully rectified in the 1.3 patch.

