When the embassy driver is poisoned. He begins seizing. But, his cardiac monitor shows no change. Not only didn't his heart rate not change. His rhythm didn't change. And his respiratory rate (also displayed as a waveform on the monitor) didn't change. And the most glaring mistake is. Even though the patient is shaking violently. No artifact from all that movement doesn't cause the slightest ripple on any of the waveforms. In a real situation, the patient's heart rate would have risen, before it crashed. His respiratory rate would have changed. And all the movement would have made a mess of the waveforms on the screen.
At the end of the episode Reddington (James Spader) opens the doors of the container they are in. That is not possible - those containers can only be opened from the outside.
Agent Keen enters coordinates into the cell phone, but she gets latitude and longitude reversed. The phone reports the coordinates represent a location in Washington, DC; but the numbers as entered (longitude 38.89 and latitude -77.0236) actually correspond to a point in East Antarctica.
The Russian Embassy in Washington DC would not and does not display a US flag outside its gate, nor would it display a US flag in its conference room or interrogation room (at 04:27).
When Elizabeth Keen (Megan Boone) is dialling a number on the pre-paid phone, we hear the number tones, but the display does not show any numbers.