In Thor, during the key sequence in which the Destroyer awakens and kills two thieves in the Asgard weapons vault, in order to foreshadow its immense power and easy violence, there's a very brief flash in the background of a familiar, devastating weapon that ties Thor to The Avengers movie via a mid-credits scene. Though Thanos will not play a major role in Avengers: Age Of Ultron (unless everyone is being lead up the garden path) this Gauntlet nod was obviously a little foreshadowing for the culmination of Phase 3, that will see the arc brought to screen for Infinity Wars.