The Lot 65 sign on the "Mona Lisa" at Art Incorporated moves from the left side of the painting to the right side.
The taxi that steed gets into at the beginning of the program is a completely different model to the one that drops him off.
In the final fight Steed hits Gregorio over the head with the 'Mona Lisa' which rips like paper. The real Mona Lisa is a wooden plank of Lombardy Poplar.
Instead of stabbing Georgie in the back, the old woman conveniently thrusts her hand over Georgie's shoulder so the woman can be flipped.
Obvious stunt man doubling for Steed during fight with Ivanoff and Auntie.
When Steed and Georgie are with Aunt Hetty in the office of John, Paul, George, and Fred when they are lying on the floor, shadows of people or equipment move across the scene.
While John Steed is asking Aunt Hetty about her nephews while she is knitting, Aunt Hetty answers without moving her lips.
Near the beginning, when Steed re-enters the taxi telling the driver, "Follow her," the camera pulls back too far and you can see the rungs at the top of the backdrop painting passing for a London exterior.