thorodinson:

The Led Zeppelin song actually was tagged right from the very
beginning in the pitch that I did. I did a sizzle reel, and kind of just
cut together a bunch of scenes and shots from films that I loved and things that I
thought tonally might help show the feeling of the film, and the whole
thing was set to ‘Immigrant Song’ by Led Zeppelin. So, that was right from the beginning. I was amazed that
they hadn’t used that song in the past, because it feels like it was
written for the Thor films. After [Marvel] gave me the job, they said we should actually do some research and find out about getting that song, just in case we want to use it. Amazingly, they got the song for the trailer and
then we also got to use it twice in the film, to amazing effect. It’s
just one really awesome song that happens to be perfect for these two
moments in the film. — Taika Waititi