I just finished rewatching it, and given the events at the end of Ant Man and Wasp, I'm curious about Dr Strange revealing the time stone. He held his fingers out and the stone began to appear. It was really small at first and grew to full size. Could he have hidden it in the Quantum Realm? Could it have been while Ant Man was there? When he went forward into the alternative futures, did that include interdimensional travel as well? An aspect of the Quantum Realm is the lack of time, so could there be some connection between the stone and the Quantum Realm?