Continuity mistake: When Blair asks Mitch "why aren't you answering me?" he says he got a weird message from Laura Barns. Blair replies "that's not funny" and Mitch replies "I'm serious." Then Blair gets a message from Laura, and when she switches back to Mitch's conversation, the last two entries, "that's not funny" and "I'm serious" have disappeared. (00:10:50 - 00:12:30)
Answer: Given the scene at the end of the film (the computer slams shut and Laura attacks Blaire) is in a POV, it should be assumed that it takes place through the eyes of Blaire.
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