Chemical Mary (No. 143) - S8-E7
Factual error: French (and other nations) ATC rely on ground-based radar to track aircraft, not GPS from the cockpit of an aircraft. Meanwhile, whilst the aircraft that had been tampered with had compromised systems, the TCAS radar on the plane flying in the other direction would have alerted its pilots to take avoiding action.
Ogden Greeley (No. 40) - S8-E8
Factual error: During the scene in a London bar, the emergency exit sign is red (and not green as required by UK law). The signs adjacent to the toilets are unlike the ones regularly seen in the UK, as are the US style light switches and a 110v power outlet in the ladies' toilets.
Dr. Laken Perillos (No. 70) - S8-E10
Continuity mistake: At the start, Reddington and Dembe are talking to a garageman. He has a protective helmet on him. They zoom in and out of him, and show him from side and front. The strap on his helmet is different every time. One time it's over his ears, one time fully above it, and the next is sits low on his ear. All this within a short minute-long talk.