At 42 minutes when Justine slips out of the brothel room, she goes upstairs and meets Lord Carlisle also going upstairs to the brothel room. In fact, Justine should have been descending the stairs because when Lord Carlisle carries on ascending the stairs, he enters the brothel room.
In the stagecoach scenes, it can be seen that in the long shots there are no passengers on board until the close-up shots.