Audio problem: Before the TARDIS materialises in the haunted house, you can hear The Daleks' time machine sound effect for no apparent reason.
The Dalek Invasion of Earth - S2-E2
Audio problem: In episode 2 you can hear the Black Dalek clear his throat before speaking.
The Dalek Invasion of Earth - S2-E2
Audio problem: When the Doctor says that what they're seeing now is the middle period of Dalek history, you can hear a metallic thing being dropped off screen.
The Dalek Invasion of Earth - S2-E2
Audio problem: When the Dalek says to give the Doctor and Ian the test, it cuts to the prison cell where you can hear a Dalek voice that gets cut off.
Answer: TARDISes are generally available for properly authorised use on Gallifrey; they're not usually assigned to a particular Timelord on a long-term basis. The Doctor stole his when he left his homeworld.
Tailkinker ★