Not content with referencing Star Wars, this series of Who also snuck in a couple of references to that other big, space-set saga, Star Trek. In Under The Lake, there is a big mural on a wall of a ship and its crew under attack from some sort of sea monster. The colours they're wearing are gold, blue, and red, a very clear nod to the three colours of Star Fleet officers. Just incase that wasn't enough, there is also the appearance of '1701B' on a chamber door. If you add NCC in front of that, you've got the Enterprise.