Other mistake: Keira Knightley looks down at her phone, there is a beautiful female hand holding the phone with long slightly curved nail beds. This is not Keira's hand which is seen many other times times throughout the film. She has shorter nailbed and flat nails. (00:22:37 - 01:13:56)
Other mistake: At the very end Nick writes "The Great" in ink above the typed title "Gatsby" on the cover of his manuscript. The E in "The" is a completely different style to the E in "Great."
Suggested correction: It is the therapist who writes The Great. As for why the Es look different, not everyone one is able to write their letters the same every single time.
Other mistake: Assange and Berg are talking to each other on Skype, and we see Assange and the view of him on Berg's screen at the same time. Even allowing for a delay, the orientation of Assange's head and his mouth movements don't correspond with those on screen. (00:29:40)