The Master is repairing the computer and when he is done, 12 circles are shown. When the Doctor goes downstairs to where the aliens are, a screen shows only 7 circles.
After the Master has asked the Doctor to listen to the drumbeats in his head, when he takes his hands away there is an obvious dirty thumbprint on the Doctor's left temple. When the camera next cuts back to the Doctor the thumbprint has vanished.
When Verity Newman is autographing her book for The Doctor, you can clearly see her pen is not touching the book as she signs it.
When The Master tells The Doctor to listen to the four beats, the metallic noise that represents it only has three beats.
American news anchor Trinity Wells mispronounces President Barack Obama's first name.