As often is the case, things change between the release of the first trailer and the debut of the movie, which could be six months to even a year in-between.
Fans have been noticing changes from The Avengers 2 trailer footage to the finished movie, such as probaly the most pointed out being the abscence of the mystery lady in the Thor cave scene (above).
Now check out a bunch more that Redditor, redditmason, uploaded to imgur.