Second appearance of Travist Polong, the orange, slug-like alien Sarah Jane was tracking in "Mark of the Berserker Part 1."
Zienia Merton who plays the Registrar previously appeared in Sarah Jane Adventures parent show Doctor Who as Ping-Cho in the 7 part First Doctor epic Marco Polo (1964). All seven episodes are currently missing from the BBC Archives (2019).
Sarah Jane mentions Metebelis III which was first mentioned by the Third Doctor in Doctor Who during the time Sarah Jane travelled with him. It would next be mentioned after this Sarah Jane Adventures story in Doctor Who by the Eleventh Doctor.
On seeing Sarah Jane and Peter kissing Clyde says "Nobody over 22 should be doing that in public!" - An obvious nod to actor Daniel Anthony (Clyde) who was 22 when this episode was made.