Sophie and Harry mention that they're on Plan M. But no one, including Hardison, mentions that Hardison dies in plan M. (This was a running gag in the original series.)
In the final scene with Sophie and Harry walking to the door of their operations building, the strap to Harry's bag is first twisted on his shoulder, then changed a little in the next camera angle, then finally is not twisted at all in the final shot. When Harry didn't move it or have time to straighten it.
In the UK airport lobby scene, an electrical outlet is visible. The outlet is clearly aligned with the North American standard, and does not look like a UK power socket.
54 seconds into this episode, as the car is speeding off, for a split second a camera man is visible in the car reflection.