When Atropos is first shown, her eyes are closed, but then she is shown with her eyes opened.
Although Doctor Diabolo charges his customers five pounds to enter the Torture Garden, and the framing story ostensibly takes place in the United Kingdom, the banknotes seen on screen are clearly US currency.
(at around 40 mins) Atropos, Dr. Diabolo's dummy of an ancient goddess, is clearly breathing in one shot.
When Peter Cushing is pushed into the wall in the cellar, the "stone" arch shakes.
At every instance when wax sculptures are shown, they are obviously not made from wax, but are actually actors and they can be seen moving. This is true for the monks seen in the background when the group is still watching the main performance, for the godess Atropos and possibly for the woman lying dead near the entrance of Diabolo's performance (she can't be seen moving, but she too is probably an actress), who is shown for just a few seconds at the start of the movie.
A still of Atropos is shown to simulate that she's not moving. A still is also used in the last story, for no apparent reason except to better show an item.