Stories subsequent to The Invasion made much use of UNIT's call signs. Brigadier Lethbridge-Stuart's include Greyhound One (Invasion of the Dinosaurs, Battlefield) and Jupiter (for the missile convoy mission in The Mind of Evil). Captain Yates is Greyhound Three (The Time Monster) and Venus (The Mind of Evil again).
The centre of operations is referred to as 'Trap One' (or 'Watchtower' in Doctor Who and the Silurians) and thus soldiers in the field are at 'Trap Two' (Invasion of the Dinosaurs). The police are 'Bluebottle' (Terror of the Autons). Particular UNIT helicopters include 'Windmill 123' (Doctor Who and the Silurians) and 'Windmill 347' (The Mind Of Evil) In The Green Death, a UNIT helicopter is referred to as 'Eagle', a general call sign for airborne operations such as the RAF in Terror of the Autons.