Revealing mistake: As Terry and Martine approach Le Sac shop, you can see reflections in the window of that shop of trees. This gives away the fact this was a custom built set (as shown in the extras) and not the real location in London. (00:20:05)
Revealing mistake: At the beginning, Griffin sits back on his chair after getting information about the first hacker who attacked their computer. He's about to put his hand on a trackball, and you can see for a second a badly covered Logitech's logo (they have left some characteristic details); the model is a Logitech TrackMan.
Revealing mistake: When Ami's chest is being drilled by the "drill-bra" at the end of the movie, you can see blood flowing from her chest, obviously because of the damage the drills are causing her. Yet, later, you can see absolutely no cuts or marks on her breasts or upper chest, where the drills were penetrating her skin. The skin is simply soaked with blood.
Revealing mistake: In the nursing home when Budlofski and Matheson are looking for Saul, we see Saul break a coffee pot over Matheson's head. When the coffee pot breaks you see coffee splash across the top of the camera.
Revealing mistake: While Punisher is killing Pittsy, you can tell he is holding a dummy, not the real girl.
Revealing mistake: The raid took place at Xmas in 1951. In homage to this fact, the characters wear big coats and one of them even rubs his hands together and goes "Brrr." Yet the movie was filmed in the height of summer. Trees in the background of scenes in London are full of leaves, we never see any mist in exhaled breath and the lighting levels and shadows indicate a high, bright sun.