When Flynn and Baird are reading the scroll from the locked case, Baird is talking about an old Librarian from the past. She says the number 400, but her lips show she said 500, meaning the number was re-dubbed afterwards.
The word "Celtic" is mispronounced by Moriarty as "seltic" instead of "keltic". The former pronunciation refers only to the Scottish football club and the Boston basketball team. Only the latter refers to the ancient culture and language group.
When Moriarty first appears in the annex by Prospero, he walks past Prospero and goes to slide his finger on the shelf as if to dust it. The actor messes up his initial slide, but completes it.