When Inspector Lau is looking at the cameras which he placed in Yeung's office through his mobile, you can see a timeline at the bottom of the screen of the mobile. Thus revealing it is a pre-recorded shot.
In the movie, we see Dr Yee's notes about Yan twice. The text in both scenes are in English and has nothing to do with Yan. In fact, the text is a discussion about a blind person who regained his sight sense. Moreover, though both text tells the same thing, the texts are not the same in those two scenes.