A model shot of Belkov's ship exploding was left out of the finished episode, resulting in some confusion as to his fate. Also removed at a late stage were a sequence of Scorpio being attacked by the pursuit ships and references to Mecron 2 being sucked into the black hole.
Filmed at Winspit Quarry, Dorset.
This is the first time Vila kills someone since Cygnus Alpha (1978), where he stabbed one of Vargas' followers.
This is the fourth episode in which Servalan uses her Sleer alias, after Traitor (1981), Animals (1981) and Assassin (1981).