When Rainsford comes ashore after the shipwreck, his clothes are wet and he falls asleep. His clothes are dry after he wakes and and travels to where he meets Zaroff, but Zaroff refers to his "wet clothes" a few minutes later.
When Count Zaroff is first giving the knife to Rainsford, he is pointing the blade at him. There is a cut to a closer shot, and the blade is now facing away.
When Rainsford and Zaroff are exiting the bedroom in a scene 14 minutes into the movie, Rainsford is quite clearly entering the door first. When we cut to the hallway, it is Zaroff who is leading the way.
When Martin is lying on the couch listening to Zaroff; his drink glass is on his chest and then falls flat on his chest. However, in the next shot, the glass is not seen and then in the next shot, the glass is back in his hand.
Though the hunt takes place between midnight and 4 am, the count can see in the dark, in a dense jungle (which would eliminate any moonlight, should the moon be out), with no flashlight or torch, a trip wire for a dead fall and the covering over of a crevice.
The island is described by Rainsford as "small as a deer park," but it contains a dramatic waterfall. Such a fall would have to have been fed by a large lake on a much larger island to flow at such a high volume.
Count Zarof claims to be a Cossack. The Cossacks were famous for their equality within the ranks. They did not have titles.
When a gunshot causes a flock of birds to flutter out of a tree, strings are visible suspending the birds.
A few seconds after Bob and Eve first enter the jungle together, the branches and leaves of a small tree in the foreground shake and sway dramatically. Whilst the tree is swaying, presumably from the wind, the rest of the vegetation in the scene is absolutely stationary.
As often happens in early sound films, the production fails to disguise the fact that the stairs and floors in stone castles are actually made of wood as the creaking and clumping of shoes in the first scenes plainly reveal.
When Rainsford arrives at Count Zaroff's fortress; his clothes had been drenched by the ocean and he has been walking through sand, hills, and dirt terrain. However, upon entering the fortress; he doesn't leave any wet spots or muddy tracks, or dirty footsteps on the floor.
When Bob and Eve are running from the dogs at a certain point the film is sped up.
When Zaroff is dying there is a shot of the dogs barking however there are no dog barking sounds.
When Bob walks up to Count Zaroff's fortress there are two fully lit torches in front of the door. He then knocks on the door and it opens up. He walks in and there is a well-lit fireplace. These are all signs of someone living there therefore it makes no sense for him to yell out if anybody is there. Additionally, since he did not open the door therefore someone had to have opened it for him. Logically one would first look behind the door to see who is doing the opening but he did not. It was only when Ivan made a noise closing the door that he turned around to discover who opened the door.
When Bob and Eve meet downstairs to enter the trophy room, Bob turns the handle and comments that it's weird that the door is unlocked. None of the characters had ever mentioned the room was kept locked, and having no knowledge of what was inside or that there was anything amiss, there would be no reason for him to expect the door to be locked.
When they let the dogs out; one of the servants has four dogs on a leash but nine others are off-leash. Logically they would all be on a leash or all of them off therefore this makes no sense.
In the opening scene the owner of the yacht insists that the captain steers a course that the captain considers dangerous. The captain of a ship is solely responsible for the ship and the safety of its crew and passengers. He does not take orders from the owner or anybody else about what course to steer.
Count Zaroff goes back and forth between his right-hand and left-hand smoking his cigarette. He also doesn't inhale. These are usually the signs of a non-smoker.