Let's see what google has to say about Statcraft 2 easter eggs...
In the Hyperion Cantina, look at the top left corner. You will see a hologram a female Night Elf from World of Warcraft dancing.
On the mission "Havens Fall," search the bottom left corner near the refugees. Just before the bottom left Zerg base in the water is a Marine frozen in "carbonite."
On the mission "Welcome to the Jungle," you can find a Murloc Marine near the left edge of the map. He's slightly north of your base. He is standing on a cliff edge, surrounded by trees.
During the mission "Piercing the Shroud," in the loading bay before the room with the Brutalisk, go outside through the door and follow the rock ledge upwards. A large area of the map will be suddenly revealed, and you will find a Murloc Marine. This is a reference to Murlocs in Warcraft
Left click any creature a few times and it will detonate