When Rudi throws the second knife at Nina it sticks in the pillar by her head. When she turns to run up the stairs the knife is no longer there.
When George lights a cigarette he holds it between his first two fingers; when the angle changes he's suddenly holding it cupped in his palm by his thumb and index finger.
In the opening scene, stage hypnotist Alex Gregor invites a drunken heckler to the stage and attempts to hypnotize him. A real stage hypnotist would never work with a subject who was under the influence because alcohol interferes with the brain's ability to receive hypnotic suggestions.
At the climax of the film, everything is explained by a character who could not possibly have witnessed the events she describes.