When Blackadder and Nurse Mary are waiting to give General Melchett their report on who the spy is, Nurse Mary is reading a newspaper type magazine. When General Melchett enters the room she places the magazine down next to her but in subsequent shots the magazine disappears from view. When General Melchett talks about a soldier poo-pooing (scoffing) officers, again she's reading the magazine and again she places it beside her again and again in subsequent shots it disappears.
Blackadder concludes that Nurse Mary is the spy and arrests her for it on the basis of her having a knowledge of the German language, asking him questions about tank movements and not pointing out that the University of Hull is not a great university. These are tenuous reasons to suspect Mary of being a spy and certainly do not amount to sufficient evidence to arrest her. It is equally nonsensical that Mary would be led to a firing squad immediately without even getting a trial.
During Captain Darling's interrogation, Captain Blackadder asks him 'What is the colour of the Queen of England's favourite hat?' but the reigning monarch at that time would have been King George V (his spouse being Mary of Teck). However, she still held the title of 'Queen' - she was merely Queen Consort, rather than Queen Regnant.
Blackadder mentions the University of Hull, which was not founded until 1927.
When we are seeing Darling's PoV as he creeps up on Blackadder in the map room the shadow of the camera can be seen on the desk.
The entire plot revolves around the search for a suspected informant in the hospital who is revealing information regarding British military movements to the Germans. Brigadier Bernard Proudfoot- Smith, who is stated to be "the finest spy in the British Army", is present in the hospital and is identified as the person who informed General Melchett of a possible informant in the hospital.
Brigadier Proudfoot- Smith was shown to be present while Lieutenant George is reading out the contents of his letters which describe British troop movements in detail. It is highly questionable why it never occurred to the Brigadier that George is the source of the leaked information.
Brigadier Proudfoot- Smith was shown to be present while Lieutenant George is reading out the contents of his letters which describe British troop movements in detail. It is highly questionable why it never occurred to the Brigadier that George is the source of the leaked information.
It is revealed that Lieutenant George is the person who has been leaking information to the Germans, albeit unintentionally. It is highly questionable why George does not face criminal charges for this act.
In the shot where George is holding the stocks the mic appears top right and is whisked away smartly.
Blackadder tells Captain Darling that there are really four verses to "God Save the King". In fact there are actually six verses. However the last verse, an anti-Scottish sentiment, is almost never sung.
General Melchett says the spy is working from a field hospital which are usually a number of tents near the front where soldiers are treated before being evacuated to a proper hospital, However the scenes concerning the search for the spy take place in a proper hospital, not a field hospital.
When Darling says to Blackadder he's as British as Queen Victoria, Blackadder replies "So your father's German." Duke of Kent and Strathearn Prince Edward was in fact English and was born in Buckingham Palace. It was Queen Victoria's mother who was German.