After Emma tells Lewis that she is leaving the college she is seen raising her mobile to her ear twice.
When Emma Golding introduces the play at its official opening, she begins her speech in bright sunlight. Suddenly in the next shot there is cloud cover, with no sign of sunlight. After that there is bright sunlight again.
Richard Scott must have unique human biology. When his body is found a knife is embedded in his chest about 6" below his shoulder blade. Later on when Lewis and Hathaway are consulting with the pathologist, she states that Scott died from a single stab wound to the heart.