When Abbey, Amy and C.J. go into a separate room to drink wine, Abbey tells the wine was a '95 wine who belonged to king Baudoin of Belgium. King Baudoin died however in 1993 so he could have never owned the wine.
In the opening sequence, while President Bartlett is working on a cross-word puzzle, he is stumped by a clue about an organ that produces Hydrochloric Acid, or HCl. Abbey responds that it is the pancreas, while it is in fact the stomach.
Lord Marbury talks to Toby about a fine Islay whiskey but mispronounces it "iz-lay". A person of Marbury's breeding and education would most likely know that it's actually properly pronounced "eye-lah" if you are from the UK.
The premise that Donna's birthplace brings doubt on her citizenship,while comical, is astronomically unlikely. Donna is from Wisconsin, which does not border Canada. For this episode it is revealed that she was born in Warroad, Minnesota which is about 10 miles south of the most distinct border anywhere between the US and Canada (the 40th parallel). For Donna's birthplace to be in Minnesota, and for that place to be subject to a dispute or realignment of the national border, Donna would literally have to have been born in the equivalent of a swamp.