Continuity mistake: The second time Hugh Grant writes on the board (not "protagonist" - can't remember the word!) the writing changes between shots - most noticeably a C in the middle, which sometimes has a small loop at the top, sometimes not.
Continuity mistake: When Hugh Grant writes "Protagonist" on the board, the writing changes depending on the shot, most noticeably the G - sometimes it looks a bit like a backwards question mark, other times it's so slanted it looks more like an S.