Captain Darling vehemently denies being a spy and says he is "as British as Queen Victoria", to which Blackadder sarcastically replies "So your father is German, you're half-German and you married a German!" In 1917 when the show is set, King George V (Queen Victoria's grandson), whose house was directly descended from German nobility, changed the royal house name from Saxe-Coburg-Gotha to Windsor in an effort to appease British nationalist feelings.
General Melchett (Stephen Fry) tells Blackadder (Rowan Atkinson) that "Oxford is a right dump". Like Melchett, Fry went to Cambridge University while Atkinson went to Oxford.
There are references in Nurse Fletcher Brown's name towards One Flew Over the Cuckoo's Nest (1975), the actress Louise Fletcher who plays Nurse Ratchett and Alonzo Brown who plays Dr Miller.