When the four surgeons visit Dr. Knox (Peter Cushing) to complain of an article in the paper, and Dr. Knox accuses Dr. Ferguson (George Woodbridge) of killing a patient, Cushing's left eye is wide open, losing its telltale droop. Later in the same scene, as well as the rest of the movie, the eye regains its droop.
When Dr. Knox uncovers the the first victim brought to him, there is an obvious cut to a new shot where the corpse can be seen.
When Dr. Knox is talking to his niece Martha near the end of the movie, in three successive shots her mouth is first open, then closed, then open again.
Just before Jamie finds Hare and Burke with their victim, a reflection of light on camera can be seen around the position of Hare's top hat.
The first victim brought to Dr. Knox clearly blinks even though it's dead.
Blood on a corpse of an old man brought to Dr. Knox looks too fresh, considering it is mentioned he died a few hours ago.
Burke can be seen carrying a box with a dead man on his back which would be too heavy for him to carry like that.
When Dr. Mitchell kisses Martha and tells her not to worry, a man can be seen moving in the background.