Continuity mistake: In "The Deadly Assassin" the Doctor's blood is red but in "State of Decay" his blood is suddenly dark blue. Then it's back to being red in "The Two Doctors."
Continuity mistake: The Doctor somehow manages to secure his scarf across the catwalk, despite having only gone on seconds before the Master. He then manages to put it on again during the seconds it takes for the Master to alter the angle.
Answer: It was never destroyed on-screen; it was intact at the end of the TV movie, and destroyed by the start of the 2005 series. It was destroyed in the novel "The Ancestor Cell," but in a completely different manner to what happened in the series.
DaveJB