Not so long ago, we were all being told by Kevin Feige that Thor: Ragnarok was going to be the last key step on the road to Infinity War. Inevitably, even with the Ragnarok and Planet Hulk storylines already warring for attention in there, fans started to assume that there would be lots of work in the story to set up Thanos' impending invasion of the MCU.
What might come as a shock to you, with that in mind, is the fact that Thanos and The Infinity Stones play a very small part in Ragnarok, and certainly not in any of the meaningful ways the theorists suggested ahead of release. There's some establishing work in there, but it's brief, sparse and insubstantial. This is a stand-alone, as alien to the rest of the MCU as Spider-Man: Homecoming, Guardians Of The Galaxy and Doctor Strange.
But that doesn't mean it's not full of references. It refers back to Thor comics lore heavily throughout, as well as to other parts of the MCU, and more surprisingly, there are pop culture references and cameos that stick out hugely. They're done with the same sense of fun and mischief as Taika Waititi seems to have built his entire film upon.
So what was in there? Bear in mind, there are spoilers for Thor: Ragnarok within. Don't read until you've seen it.