The housekeeper replaces the handle only on the outside of the door, so when Lt. Gates goes to open it from the inside (after Rochard claims it was broken), the inside handle would not have been in place.
Catherine is sometimes referred to as Captain (her rank is Lieutenant).
When Rochard and Gates pull up to drive onto a small river ferry, two large river barges/boats are tied up along the shore to their left. Houses and buildings can be seen for some distance. When the ferry reaches the opposite shore, however, there are neither boats nor buildings, but an open rolling plain with patches of trees.
With Catherine gone briefly, Henri is waiting and sleeping in the sidecar when some children put the motorcycle in gear. With no driver, the motorcycle increases in speed and shifts gears.