Chase is obviously under Krynoid control. The Doctor suspects possession but, with the mountainous Krynoid nearing maturity and whacking the mansion to pieces, he concerns himself with the bigger picture and orders the mansion - with Sarah and him still inside - to be bombed. Written by
Did You Know?
The episode also marked the final major appearance of UNIT in the series until 1989's Battlefield (although it would be referenced in the Fifth Doctor story Time-Flight, Brigadier Alistair Gordon Lethbridge-Stewart appeared in the 1983 story Mawdryn Undead as a retired civilian, and there is a sequence set at UNIT HQ in The Five Doctors). None of the established UNIT characters are seen in UNIT's brief appearance in this story, as it was felt that there was too little material to warrant bringing back the Brigadier and Sergeant Benton. See more
When the Doctor and Sarah Jane escape the composting room and go running to the door outside, the Doctor bumps the wall, causing the top corner to wobble conspicuously. See more
Sir Colin Thackeray
Well, Doctor, do you think we've heard the last of the Krynoid?
Sir, Colin, the Intergalactic Floral Society - of which, quite naturally, I'm the president - finds Krynoids a difficult subject to study. Their researchers tend to disappear.
Sarah Jane Smith
Hmm, I can imagine: a case of one veg and no meat.