Plot hole: Blore's death is fairly absurd, since the killer couldn't plan that he'd be standing, with all the possible room outside of the house, exactly in that spot at that distance from the window, with a ton of bricks that are precariously balanced on stone spheres that survived storms and heavy winds but somehow are loose enough to require a gentle push to fall down. (01:25:30)
Other mistake: In the flashback of the denouement, Dr. Armstrong is shown dead face down on the beach, with the feet pointed ashore and the head to the sea. Mr. Owen takes also a sip from that Armstrong's flask and tosses it in the sand without capping it. However, Vera and Lombard found a corpse face inland and feet to the sea, and a flask with its lid in place. (01:28:50 - 01:34:40)
Continuity mistake: During the confrontation between Vera and Lombard at the beach, their hair is windblown with intensity that changes at every cut. (01:29:05)
Continuity mistake: On the beach, Vera and Lombard are quite literally pointing fingers at each other...except they are not; new shot, different pose. (01:29:10)
Continuity mistake: When the 'sole' survivor walks into the supposedly empty house and spots the noose, it is placed quite high. When they walk back into the room with Owen, the noose is dangling low enough to nearly brush against his head. (01:31:35 - 01:32:25)
Revealing mistake: Mr. Owen's dramatic appearance begins with a precise pool shot. But Owen is standing behind the table in a position incompatible with the angle the ball was shot from - someone else out of frame must have performed that shot. (01:31:50)
Plot hole: Spoiler; Under the pretense to help catching the murderer, the Judge goes through great lengths to enlist the help of the doctor to fake his own death. In this adaption it's made moot by the fact that the murder happens in the living room, his body needs to be carried upstairs and we even see that happen, with all the remaining survivors hauling the 'corpse' in their arms. One thing is faking with a little make-up (literally a paste-on red dot) to be shot in the head, with just the accomplice examining the supposed corpse, and the others at distance and with bad lighting. But with everyone carrying the body, including a police inspector and a PI who are accustomed to violence and real murder, it's plain impossible.
Character mistake: The killer in the original novel (and as reminded also in this adaptation) stages his homicides following the nursery rhyme; goes through great lengths to do that, including planting a bumblebee in the room, using a hatchet, etc. But Blore's death has nothing to do with a bear, since he gets crushed by bricks. Conveniently the rhyme is not mentiones by the characters at all for his death, while they were the first ones to recite the matching verse in all the other deaths. In the original novel, Blore gets killed by a heavy object shaped like a bear.
