At the end of episode 12, when Shaw and Sarah drove away, Sarah had curly hair. Minutes into the beginning of Episode 13, Sarah is seen with straight hair.
In the final scene where Chuck and Sarah are sitting on the bed in the hotel room in Paris, when the camera pans away you can see that the view of Paris through the window is either a backdrop or green-screened.
When Chuck and Sarah were outnumbered and outgunned in the elevator Shaw comes to their "save" but later on this all turns out to be a trap to capture Sarah. Since she was already captured and held at gunpoint at the time of Shaw's fake rescue, the whole scheme was unnecessary and pointless.