Deliberate mistake: During the interrogation scene, a patient asks for a glass of water. When she receives a the glass of water, she lifts her right hand to her mouth and makes a drinking motion, but is not holding a glass. A moment later she sets down an empty glass with her left hand. When the camera angle changes, the glass has become half full. This implies the patient's mental instability and adds to the surreal feel of the film.
Continuity mistake: When Teddy's kids are lying dead on the grass, the position of the girl's arms keeps changing between shots.
Teddy Daniels: Baby, I love this because you gave it to me, but it is one fuckin' ugly tie.
Trivia: When Teddy enters the lighthouse, as soon as he begins to climb the spiral stairs, the camera follows his movement from in front of him. However, as Teddy and the camera wind around the stairs, the wall behind also appears to move with them, as though what is REALLY moving is only the staircase itself, rotating on its central axis. Yet another point (added to the various disappearing glasses/bottles) that adds to the general 'insane' feel of the film.
Question: Why does Teddy have a cut with a plaster (band-aid) on his forehead throughout the film?
Answer: He was in an altercation with the patient in ward C prior to returning to ward C and talking with him again. It was an injury sustained in the past due to that.
Answer: The bandage is a symbol indicating when and when not Teddy is caught in his delusions. When the bandage is on he is delusional, thinking he is the marshal finding out all the dark secrets of the facility. When the bandage is absent he is lucid and aware of his past crimes and his own delusions.
Wrong. It's on the whole movie until he takes a shower. The bandaid is off but yet that's the scene where he runs in the lighthouse thinking he's the Marshall still. Did you watch the movie at all?