After the projection room is 'destroyed' you see the shadow of a minion. He starts to make shadow puppets, including one of Gru. You see the shadow of the actual Gru enter the screen and stare at the minion. The minion runs off in panic and Gru starts laughing.
During the Illumination opening title, a Minion walks on screen and says hi to the audience, until the Illumination logo brightens up and stuns his eye. He then faints forward and proceeds to crawl off screen.