Continuity: When the three Russian negotiators meet Ninotchka at the train station in Paris, the white ticket tucked into her jacket changes position from shot to shot.
Continuity: When the Russian trio are drunk, the glasses fall off of the man in the middle, and in the next shot they are back on him
Errors made by characters (possibly deliberate errors by the filmmakers): During the telegram/kissing scene, Iranoff refers to Bela Lugosi's Russian Commissar Razinin's name as Razin while Leon and Kopalski refer to it as Razinni, a distinctly Italian name. When it is mentioned again at the train station by Ninotchka, she again mistakenly pronounces it as Razinni. It isn't until later in the film that the correct pronunciation is used.
Errors in geography: The French bottle of milk has a label only in English
Errors in geography: The Soviet censorship stamps on Ninotchka's letter are in the Latin alphabet, in English.
Continuity: When the three negotiators are drunk and Leon stands up, he at first does not have the letter in his hand, but then it appears.
Continuity: When ordering cigarettes, one negotiator is beside the desk and two in front, but then it changes to two beside and one in front.
Continuity: After arriving at the suite, and Ninotchka begins typing, the position of the trio and the manner in which they hold their hats change.
Continuity: When the three negotiators are on the train platform looking for their comrade from Moscow, their positions change. This happens two times: when they see the man who is actually a Nazi and also when they meet Ninotchka.
Continuity: When Ninotchka tells a funny story, objects on the desk change positions.