Visible crew/equipment: When Benny comes home from work and Mrs Smail is about to leave there is a crew member leaving through and closing the backdoor. He has short blond hair, and looks to be thin and a bit on the tall side.
Suggested correction: That is not a crew member. It is Joon, leaving and slamming the door after her argument with the housekeeper. The fact that we can hear the door slam shows it was not an error.