How did Fluerot know Carmichael had thrown a book at Constance?
Trivial, but stuff like this bugs me. He walks in after the confrontation between Carmichael and Petersen and says something like "I feel a bit like Carmichael, I want to throw a book at you".
I can only assume he was watching through the keyhole. Come to think of it, he DID get in the room pretty damn sharpish when Carmichael started throwing a wobbly.