When Kamelion (under the guise and influence of The Master) takes Peri out of The Doctor's Tardis and towards his own, a rockfall knocks him unconscious. He later awakens with a sore head. But Kamelion is a metal robot, who has only assumed the shape of The Master. He isn't flesh and blood, as Peri discovered when she tried to kick him a few minutes earlier, and therefore would not feel physical pain or be knocked unconscious.
At the start of the first scene (1m 13s) within the great hall on Sarn where Malkon tells Timanov to release the unbelievers, Edward Highmore who plays Malkon is looking directly at the camera, no doubt waiting for a cue.