When Leslie and the others leave and Leslie shuts the door, Howard walks through the door twice.
When Leslie enters her bedroom for the last time, she locks the door behind her. Later, the door is unlocked when Robert enters.
When Howard Joyce is in his office talking to Robert Crosbie, he is sitting on the arm of a chair and holding a cigarette with his right hand. On the next immediate cut though, when he stands up, the cigarette is in his left hand.
The light source off Leslie's room is directly in front of her, but when she is in the garden it is to her right and not as bright.
There is a running theme of Leslie looking at the moon. Many of the shots show a full moon in the exact same relation with the same palm tree despite Leslie looking at it from different locations. Towards the end, she looks up from the back door of her bedroom, a few minutes later she looks up from the middle of her back yard, and again a moment later at the back gate. The moon and palm tree are the same distance apart in each shot, but even in that short span of minutes, the moon would have moved perceptibly in the sky. Also, the position of the palm tree should have changed significantly from the parallax of her different viewing spots. Obviously, the moon shots were taken from a stationary position instead of using different setups for each place Leslie was standing.
The patio off Leslie's room looks to be covered (as evidenced by hanging lamp and columns); therefore, she could not look up to see the moon from the doorway.
It makes little sense for the European/American characters to be cloaked, under stifling Malaysian weather, with what are clearly, buttoned-up wool and gaberdine, double-breasted suits. The plantation workers are understandably only wearing shorts or light clothing. This seems like a poor choice from the wardrobe department.
In the Chinese quarters when Mrs. Hammond is first seen in the room behind the bamboo curtain, the door behind her is open. However, a moment later, a crew member is seen quickly closing it.
We see Leslie faint and taken to see the nurse. The nurse leaves the room and Leslie is talking to Howard Joyce, but behind Mr. Joyce is a shadow of a piece of equipment or crew visible on the room divider behind Mr. Joyce. The equipment is pulled back and the shadow disappears.
The motor vehicles throughout are all left-hand drive. In Singapore traffic drives on the left, and all vehicles there are right-hand drive.