As the Doctor and Master struggle on the gantry, the Doctor's scarf snags on the structure, and, as the Master breaks away and returns to the cabin, it falls to the decking, some distance from the now prone Doctor, who continues to crawl on.
In the next shot, showing the view from the cabin-end of the structure, with the Doctor crawling away, he is suddenly wearing the scarf again.
In the scene inside the control room when the Master is broadcasting his demands, he has his weapon in his left hand. In the close-up of his face, it has shifted to his right hand. In the next normal shot, it is back in his left hand.
Adric tells Nyssa that radio telescopes are used to beam messages to the stars. In actual fact, the primary purpose of radio telescopes is to *receive* radio emissions, not transmit them.
As the Doctor makes his way out onto the aerial gantry, the "Master" that is watching him go is obviously a superimposed still picture of Anthony Ainley.