In the preview trailer for the next episode, In the Forest of the Night, we see a London bus in the forest. If we look closely, we can see what appears to be a promotional shot of The Doctor and Clara with the quote "A-Maze-Ing Entertainment!" and four stars below it.
Here is the original piece that the art belongs to. This is a fan-made wallpaper photoshopped from the official promotional images released early this year. The creator, Logan Fulford, originally uploaded the wallpaper to his Flickr account late January. It can be noted how we don't see the logo on the bus.