Before his departure from the show after Family First (2016), this is the first episode not to feature Michael Weatherly, as he was busy filming the pilot for "Bull." The absence of Tony DiNozzo is explained by a trip to Russia, through which he actually lends various clues to the team without actually being present.
On Jessica Terdei's MI6 application form, her home phone number begins (020). While this is the current dialling code for London, in 1984 when the document was written it would've been (01).
Also, although the dialling code for Warwick (where her next of kin lived) would've been 0926, they've correctly used 01632 which is the code used in UK TV shows in the same way US shows use "555-XXXX".
The English pub scene has a smokey look to to air, though smoking has been banned in English pubs since 2007.
Reiko Aylesworth played Mrs. Marshall in this episode. Hawaii Five-O is part of the same universe due to crossovers that both shows have had with NCIS: LA. Reiko plays Malia Waincroft in seven episodes of Hawaii Five-O.
Reiko Aylesworth (Hawaii Five O) played Anne Marshall (Henry's mother) and First Lady Michelle Obama played herself in this episode.