Continuity mistake: For a second time in the movie, someone buzzes June on the intercom. She tries to overcome her fears and get out of the apartment, but can't. She shuts the door, leans with the left hand on the doorframe by the chain, and lowers her arm. In the next shot, Naomi Watts is breathing deeply still with her hand by the chain. (00:06:05)
Continuity mistake: At the beginning of the basketball game, there's someone in a red hoodie and a baby mask sitting directly next to Ryan. A few shots later, you can see over his shoulder, and there's someone else entirely next to him - a woman without a baby mask wearing an entirely different top. Then, a little later in the scene, the person in the baby mask and hoodie reappears next to Ryan in a few wide-shots.
Continuity mistake: The cigarette the homeless man offered to Frank had a brown filter but was white when Frank had it in his mouth. (00:39:10)
Continuity mistake: After the cartoon segment, Deni entertains some playful banter with his girlfriend and takes off, putting a shirt on while he runs. When the neighbour asks him "Late again?", the guitar strap is on opposite sides of the instrument as the editing switches to a reverse shot. (00:06:40)
Continuity mistake: When Charlie throws Scott over the balcony, he crashes into the chandelier and it partially tears away from the ceiling. Sparks ensue, but the light remains fully functional. The camera switches to Scott on the floor then back to Charlie where the chandelier can be seen worth all but one light out. There is no visible difference in the room lighting. Later, when Charlie is chasing Scott and Annie with the shotgun, Charlie screams "Lights out!" and shoots a fully functional chandelier.