Containment - S1-E5
Continuity mistake: At the end of the episode, when the bad guy is preparing the syringe of small pox, he follows the usual method of tapping out any air in the tube - when he is shown injecting himself, a large air bubble is back in the syringe (which would probably kill him quicker than the smallpox).
Continuity mistake: When Marshall first finds Trip's letter, he holds it from the left side. In the close-up, he's holding it from the right side. (00:02:10)