When Jessica is having her final showdown with Mr. Styles alias The Cobra, she makes the deduction that the postage stamp on the card must be very rare. To which replies: "Unique. There are only two others just like it." But, this is a contradiction in terms, as the dictionary defines "unique" as, quite literally, one of a kind.
In one of the jail cell scenes where Jessica is reading the Zane Grey novel, State Department Agent Styles comments, "I see you're a (author's name) fan". But when watching the scene with subtitles on, the spelling is changed to Gray, thereby not matching up with the spelling printed on the book.
At around 37 minutes the camera, operator and lights can be seen reflected in Leslie Easterbrook's sunglasses. The red light showing the camera is filming is readily visible.
At one with Jessica in jail, a man, dressed as a policeman tells her he's a counter-intelligence agent.