Other mistake: What happens to Tegan's bag when the plague victim transforms into the cavalier? It doesn't appear to be left behind, even when the cavalier later vanishes.
Resurrection of the Daleks - S21-E4
Other mistake: When the Doctor's mind is scanned, we see his previous incarnations and companions, but Leela is not shown. Katarina is represented by a black and white photograph.
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