Oh, there was plenty else. The main part of that 'else' had to do with what was in the room the Master was to find later. But the Doctor couldn't tell him now. He couldn't let that out, not yet.

Later.

"I've set the cameras in this area to randomly flicker off and on, along with the rest of the power," he said. "Feel free to mock him about shoddy workmanship, he built this place himself and it will drive him mad."