The script that Terry Nation turned in was severely under-length. Script editor Chris Boucher had to fill the script out considerably to make sure it could take up a full episode. One of his editions was the character of Tyce. The scene where Blake breaks Sarkoff's records was also added to pad the episode out.
When Avon agrees with Vila's opinion on the distress call, Vila murmurs "Makes it all seem worthwhile." This becomes a recurring theme between the two characters, with variations on the line being used by one or the other in Gambit (1979) and City at the Edge of the World (1980).
The Waterloo Tower in Quex Park, Birchington, Kent was used for Sarkoff's residence. The doors were painted white and gold for the episode, and they remained that colour for many years afterwards, although they have now been painted over.
Gareth Thomas actually performed the stunt where Blake scales a wall. On one attempt, part of the wall collapsed and he was left swinging in mid-air.
Jan Chappell's stunt double Roberta Gibbs injured her ankle while filming the stunt where Cally leaps from a wall to attack a guard. She completed the stunt before going to hospital.