Other mistake: When Alice asks Dan to make her some tea (after he tells her about him and Anna), he walks into the kitchen for just a moment, and comes back to find her gone. He also doesn't see her as he runs downstairs and looks outside. She couldn't have quietly gone down the stairs and out of the building in the short moment that Dan was in the kitchen. If she had moved quickly, there should have been a lot noise from her footsteps.
Other mistake: When Anna takes her first picture of Alice, she lifts the camera to her face, then the shot changes to faraway, and she lifts it to her face again.
Other mistake: At Anna's Exhibition, when Natalie Portman is smoking a cigarette, she's smoking a Red (Marlboro), but we can see the White Marlboro (Lights) box when she offers one to Larry (Clive Owen).
Suggested correction: No he's not.
The mistake is valid. After Larry says "Buster", we see Dan standing at an angle with his back towards the opening of the door and doorknob and his left side closest to the door. In the next shot, he's turned more than 90° so that his right side is now closest to the door opening and doorknob.
Bishop73