Marvel Studios president Kevin Feige's comment about the Eye of Agamotto's time-bending properties may hint at a connection to one of the remaining Infinity Stones: the Time Gem.
"In this film, the Eye is a very important relic that can be quite dangerous if used in the wrong hands, because it has the ability to do any number of things, the most dangerous of which is, it can sort of manipulate probabilities," Feige told Entertainment Weekly during an interview about "Doctor Strange." He then clarified, saying, "Which is also another way of saying, ‘screw around with time’ -- which is part of our story."
In "Avengers: Age of Ultron," Thor (Chris Hemsworth) had a vision about the Infinity Stones. By the time of "Ant-Man," four of those Infinity Stones have been discovered: the Mind Gem (Loki's scepter); the Space Gem (the Tesseract); the Reality Gem (the Aether from "Thor: The Dark World"); and the Power Gem (the Orb from "Guardians of the Galaxy"). That means there are two gems left to be discovered: the Soul Gem and the Time Gem.
If what Feige says about the Eye of Agamotto's ability to warp time is true, then there's a chance Stephen Strange may have found himself in possession of one of the last two remaining Infinity Stones: the Time Gem. However, we won't know for sure until we see it in action in "Doctor Strange."