Revealing mistake: When Victor and Margaret arrive back from her goddaughter's, they find their new wallpaper has been stripped. Margaret then goes up the stairs to bed and through the arch window you can see her stop at the top of the stairs waiting for the scene to end.
Visible crew/equipment: On the train at the start, after everyone has left except Victor and Margret, you can see a boom operator reflected in the door's glass panel. You can see him and it's even more noticeable when he lowers the boom for when Victor sits down. (00:04:05)