Originally Posted by Hammer!
Anybody listen to Fiege/Hiddleston's commentary track? Apparently the Prologue was added after first screenings, and Loki's intro was added a couple months before the opening. Makes me wonder how the heck this film originally started. Jane's lunch date? Vanaheim battle?
I haven't heard it as I only have the digital version but I'd assume there was something else in place to give a bit of information. It would be hard to understand the plot if you just remove the prologue and don't add any other info.
Other than that I think the Vanaheim battle was probably a very early scene, and likely the full one. I can imagine that they cut it down to not delay Thor's entrance too long into the movie when they added two other scenes before it.