When Sydney meets the bank manager she reaches to remove her sunglasses with one hand. As the shot changes she's suddenly using both hands.
The picture Nadia shows Sloan is not the same that she shows Jack (2nd time).
In Spain, we can see a sign which reads "Elevador", which means "Elevator", but that word is mainly used in Latin America. The correct word in Spain is "Ascensor".
When Vaughn is using a directed microphone to communicate with Sydney, he continues to talk to her while focusing the microphone away from her, which should break their line of communication.