It was revealed in Avengers: Infinity War that Eitiri was forced to forge the Infinity Gauntlet for Thanos, but some think that, since Nidavellir has long been under the protection of Asgard, it should have been impossible for Thanos to have been given the Gauntlet by Eitiri all those years ago when Age of Ultron came out.
This is your last chance to avoid spoilers, so stop reading now if you haven’t seen Avengers: Infinity War yet.
Avengers: Infinity War essentially marks the beginning of the end for most of the Marvel Cinematic Universe as we know it, with Thanos (Josh Brolin) going on the hunt for the Infinity Stones to use with his Infinity Gauntlet.
Joe Russo clarified that the Age of Ultron post-credit scene did in fact take place in Nidavellir.