A mysterious tattoo
Some of the surprises in the MCU films don’t require much digging to figure out. Some of these references are so glaringly obvious that you’d probably wonder how you missed it. Others are a lot more subtle, and perhaps only the most diehard MCU fans would even bother to notice. For instance, the Ten Rings logo pops up on multiple occasions.
In one scene in Ant-Man, we can see one of the terrorists with a Ten Rings tattoo on his neck. This is a subtle hint that the terrorist organization is still active, despite being on the receiving end of an Iron-Man beating.