In the closing scene, there are several references to the film Goldfinger (1964), which Honor Blackman would appear in following her departure from the series. In that scene Steed mentions something about "pussyfooting."
Last one to be recorded on videotape.
Cathy reveals her address as 5 Westminster Mews. In fact, this is John Steed's London address, and she is deliberately attempting to mislead; it is because the address is recognized by Mason as Steed's that her bluff is ruined.