Good idea! Thanks! Yes the facts can get confused with speculation, that's for sure.
Official Synopsis Marvel’s Thor: The Dark World
continues the big-screen adventures of Thor, the Mighty Avenger, as he battles to save Earth and all the Nine Realms from a shadowy enemy that predates the universe itself. In the aftermath of Marvel’s Thor and Marvel’s The Avengers, Thor fights to restore order across the cosmos…but an ancient race led by the vengeful Malekith returns to plunge the universe back into darkness. Faced with an enemy that even Odin and Asgard cannot withstand, Thor must embark on his most perilous and personal journey yet, one that will reunite him with Jane Foster and force him to sacrifice everything to save us all.
Adewale Akinnuoye-Agbaje has at least once scene with Renee Russo and Anthony Hopkins per his twitter. Anthony also has had "one encounter" with Chris Eccleston per a recent interview with Anthony.
There is a big red bus with the film title "Moral Sacrifice" on it in the film. The name Rhys Ifans is also listed on it giving a review blurb about the film, along with a bunch of behind the scenes people. Stan Lee will be driving the bus. (or is that just a rumor still?)
Richard Brake will be in it as an Einherjar Captain
Alice Krige has a small role where she may be "unrecognizable"
Malekith and Thor battle each other at least once in the film.
A set and battle scenes were filmed in Bourne Woods involving Asgardians, and a very varied group of characters and creatures.
A scene or scenes were filmed at Stonehenge
The alternate filming name for Thor The Dark World is Thursday Mourning
The film will have a "Game of Thrones" feel/vibe (per Chris Hemsworth, and I think others have said this as well...)
Thor and Loki "get down to the major bones of our conflict with everything that’s come from Thor to Avengers to now.” - Chris Hemsworth
interview Nov. 2012
"Going into this one we (w/Chris Hemsworth) were - very flatteringly - involved in big creative conversations about tone, and story. Thor and Loki are these two characters that people know and love and understand - so we have to take this in the right direction. You want to do something new - you don't want to re-heat the same recipe in the microwave, you want to cook up something different and exciting - but you don't want to lose the things that worked the first time." ~ Tom Hiddleston
GQ UK interview 11/14/12
"Everybody upstairs in space is going to have an opinion on what happened over the course of Avengers" ~ Tom Hiddleston
interview 11/12 http://bcove.me/n5b8dygl
(and please let me know if you dont think any of this is 100% fact and I will remove it)