Visible crew/equipment: When Marion is packing in her room, the camera is panning back over the bed to show the newspaper with the cash wrapped up in it. As the camera pans back, one can see the camera's shadow on the bed.
Visible crew/equipment: While Janet Leigh is being stabbed to death by Mother, as Janet turns around in the shower, it is possible to see part of the moleskin that Janet wore for the scene for a split second. (00:47:30)
Visible crew/equipment: When Marion arrives at the car dealership, the salesman sees her and starts walking towards her. If you look carefully, there is a wire trailing out his trouser leg, most likely for a hidden mic.
Visible crew/equipment: When Marion arrives at the car dealership and the salesman says "be with you in a second", pay attention to Marion's car door. You can see the reflection of a crew member kneeling down as soon as she starts walking away from the car.
Answer: Norman and his mother lived together in the house on the hill above the motel. Norman's mother was such a demanding, controlling, overbearing woman that Norman was eventually driven to kill her. The enourmous guilt of this action, combined with the strain he was already under from her treatment of him, caused him to develop a sort of modified split personality: in addition to the existing Norman, he constantly heard his mother's voice in his mind and even had conversations with it. As time passed, the "Mother" voice in his brain began to have some occasional control over his body. Thus, sometimes Norman was in control, sometimes his mother was in control, and sometimes they could "speak" back and forth within his mind. Norman checked Marion into the hotel, but the sexual attraction caused by her presence made his disapproving Mother personality manifest and kill Marion. Having dealt with the situation, Mother retreated and Norman cleaned up, not remembering. At the end of the film, Mother blames Norman for the crimes because she is once again controlling his life and not wanting to take the blame herself. At the same time, this represents Mother forcing Norman down to some corner of his consciousness or even destroying it altogether, meaning that it is unlikely that Norman will ever manifest control again. This is why we hear Mother's voiceover and not Norman's at the end.
Phoenix