Plot hole: We twice see a map of how far the ice is away from the house, once in the first episode, and later in episode five. The ice has moved most of the way across the map in this time, and the distance it has moved is stated to be a 100 metres. This would place it only 20 metres from the base. The problem with the distance is that it takes Penley quite a while to get the injured Jamie to the base, including a stretch across open ground. Also, The Ice Warriors weapon targeter suggests the base is as much as two kilometres away. So just how far away is the ice; 20 metres, 2 kilometers...or somewhere in between?
Plot hole: When the airlock door is opening at the end of the final episode, the Cyberman is the only one who appears to be affected by the air rushing out. Although 'rushing out' is probably overstating the speed of the 'explosive decompression'. It's not so much an explosion as a gentle breeze...
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