When Graham is interviewing Ann, Ann sets the camera down
on the arm of the chair pointing at the window away from the couch. When Graham gets up to turn it off, it is pointing at the couch.
When the sister enters the apartment, he is holding a blue dart. When he throws the dart it is red.
When John bursts into Graham's apartment, he finds Cynthia's and Ann's tapes in the boxes on the table. Both tapes have the same date on them, even though it is clearly implied that several days have past since Cynthia made her tape.
In most videos, the camera moves constantly during the interviews, as if hand-held. In almost every interview we see, Graham sets the camera down before starting their discussions.
Graham and Anne's hands when they discuss therapy in the cafe.
When Ann asks John if he is having an affair, Ann says "alright, alright you've made your point," but her lips move out of sync.
Briefly visible in the top right corner of the screen right before John's "It's so blatantly stupid" line.