Now as we know, Benicio del Toro told us in an interview, that he wod not be in GOTG2 as the Collector. And before GOTG2, we know that Thanos has the Infinity Gauntlet, but none of the Infinity Stones!!
Now we know where four of them are.
1) Tesseract- Thor took the Tesseract back to Asgard, with Loki.
2) Mind Gem- Currently in Vision's head.
3) Power Gem (Orb)- The Guardians of the Galaxy handed it into the hand of the Nova Core.
But I know what you're thinking, I said 4. Well, none other than The Collector has the fourth
and final Infinity Stone, the Aether. If you watched Thor: The Dark World, First of all, I'm so sorry, Secondly, In the mid-credits scene, The Asgardians took the Aether to The Collector, himself. If anyone actually saw the Aether in GOTG, comment below, but I didn't see it. This must mean we still must see Thanos go to the Collector's destroyed museum, and take it from him. Will we get another credit-scene in Civil War, or maybe Doctor Strange? Let me know!!