In real life, one of the lesser-known members of the Ministry of Ungentlemanly Warfare was Sir Christopher Lee. Lee was a step-cousin of Ian Fleming, and Fleming first suggested him for the title role in Dr. No (1962) while golfing together. The part went to Joseph Wiseman instead, but Lee ended up playing another Bond villain - Francisco Scaramanga in The Man with the Golden Gun (1974). Also, Lee famously used his experience in the Ministry operations to educate Sir Peter Jackson, when filming the Lord of the Rings trilogy, on the "sound a man makes when is stabbed in the back."
In the 1968 Kingsley Amis novel Colonel Sun, James Bond says he once spent several months serving aboard a Brixham trawler, suggesting he was a member of the British Small Scale Raiding Force party that conducted Operation Postmaster, the same operation depicted in this film.
Easter egg: U-96 from "Das Boot" makes an early appearance.
The closing credits reveal that Gus March-Phillipps was one of the inspirations for James Bond. Henry Cavill was a finalist to play Bond in Casino Royale (2006), but was rejected for being too young (he was then 22). This is the third film in which Cavill plays a Bond-type character, after The Man from U.N.C.L.E. (2015) and Argylle (2024).
Ian Fleming introduces himself, "Fleming. Ian Fleming." This is a nod to his fictional hero James Bond who, in many of the films in which he appears, introduces himself as "Bond. James Bond."