Revealing Mistake: When Jamie opens the door to go after Victoria and sees the Yeti, the entire wall shakes.
The Doctor: Don't be foolish, Jamie!
Jamie: But Victoria!
The Doctor: She will be your responsibility. And when it's all over, you'll just both have to look after me, that's all.
The Doctor: Well, if what the Intelligence says is true, my mind will be like that of a child. You'll have to look after me until I grow up.
The Doctor: No, don't shoot!
Evans: (up on a chair) Is that thing on our side, then?
The Doctor: It is now. Stop. Were you scared?
Evans: Eh? Oh no, no, I mean, I just got up here to get a better aim, that's all.
Lethbridge-Stewart: Evans, come out from behind that board.
Evans: Oh, it's you, sir.
Lethbridge-Stewart: Where's the Doctor? Evans!
Evans: B-b-but y-y-you, you...
Arnold: Stop bleating like a Welsh baa-lamb, Evans, and answer the Colonel.
The master copy of this episode was wiped in or shortly after September 1969. A 16mm telerecording of the episode was recovered from Nigeria in 2013.