I think this new who viewership have become accustomed to everythings being spoon fed rather than left up to the imagination.
Durin the episode in that tongue section, the doctor says that the tubes going from the polling stations with the "forget" "protest" buttons were surgically inserted into the tongue, there were more than one, and on the tube where the doctor coomes through there are red lights surrounding the opening. So its saffe to assume the other tubes also have red lights, hence why the lights appeared all over.
Nothing too major, but not something moofat thought he had to write in a reference
"well Amy, as you can see behind me, hundreds of red lights, on the tubes, like the one we came through, and anyway onto escaping.."