Continuity mistake: When Martino is wandering the desert, delirious from the heat, his shirt is unbuttoned to half his chest or lower. When he is shown dead in a longshot, his shirt appears buttoned up higher than that. (00:51:05 - 00:52:20)
Revealing mistake: Oliver Reed heroically pummels a venomous snake made of rubber (therefore invulnerable to his heavy hits). (00:58:30)
Continuity mistake: Blore is reluctant to admit his guilt. He stands up but the Judge bangs his cane angrily on the floor and Blore sits down again. The candles in front of the Judge have a different length between shots. (01:07:40)
Other mistake: Throughout the 'blackout', no lights at all work and everyone has to get by with candles, torches and their own flashlights, but the main hall is perfectly lit, and even when they go rescue Vera who cried because her candles were blown out, the corridor behind Lombard has enough light to allow anyone to see without any problem. (01:11:10)
Revealing mistake: When everyone enters the Judge's room and looks at him lying lifeless in bed, the room is in the dark. The light increases when the candles have been on the bedstand for a couple seconds already. (01:12:50)
Continuity mistake: And then there were four. During their tense conversation in the lobby, the Doctor gets close to Lombard, who has his jacket in hand. He holds the jacket in a different way (sideways vs more frontal) in the two different shots. (01:15:00)
Continuity mistake: Lombard asks the Doctor how would he know what was going through the Judge's mind, and Armstrong answers "I know because he took me into his confidence." Behind him, Blore is hunched over, with both hands together over the table. Armstrong turns his attention to Vera, and Blore now is sitting in a different pose, with his chin over his hand. (01:15:10)
Continuity mistake: Vera gets in her room with the other three 'Indians' outside. She carries no candles or other mean of illumination. Yet in the scene when she strips, starting right past the door, the room is brightly lit and a candelabrum is on her bedstand. Her candles went out during the incident that made her scream, so it makes no sense that there'd be warm light waiting for her in her room. (01:17:00)
Continuity mistake: Lombard and Vera are in bed together, in a much chaste way (he's wearing a full turtleneck). He tells her that he found the letter in his friends' belongings. Her hand is on her own cheek, but at the cut (happening while she is mid-sentence) her hand is on his arm as he reached down to cope a feel. (01:22:25)
Continuity mistake: Four suspects are left. To check the noise, Vera insists with Lombard saying "I wanna go with you." Notice that one of the three candles in the candelabrum is not lit - the flame fizzled out when she walked too briskly from the bed to the door. In the corridor though, all three candles are burning. (01:23:10)
Other mistake: Despite Blore having shorted out of the generator the night before, when the last survivor gets back to the hotel for the finale, all the lights in the lobby are back to normal. The killer is smart, but not an electrician. (01:30:25)
Audio problem: When Mr. Owen does a shot of billiards as he starts to explain the evil plan, there are just two balls left in total (the cue ball and an object ball). The shot happens off-camera, but the sound dubbed in implies that one of the balls clashed with a third one. (01:31:30)
Other mistake: The end credits list the cast, so it says, "in order of their disappearance." But it's not true; Ilona is listed before Martino, who disappeared earlier than she did (52:30 vs 58:20), Blore is listed before Armstrong, who's been dead longer, and Lombard is the very last, while he was the Indian number two.
Plot hole: In this adaptation, set in Persepolis, the killer couldn't possibly predict that the third-to-last Indian would use binoculars to check out of the corpse in the ruins, and he'd have to lurk in the ruins, with very limited to non-existent cover, in the sun, for a chance to push someone much larger than them, who also happens to be on their own.
Plot hole: The way Judge Cannon joins the ranks of the dead in this adaptation makes the most sense of all the others, since he dies in his bed fixing a variety of logic mistakes, but it suffers from a flaw found also in the 2015 BBC adaptation; Vera screams because her candles go out, which is not something the killer could have set up, as opposed to the scary items planted by the killer in the novel and in previous movies. Without it, the killer couldn't have devised the plan the way it is shown.
Plot hole: Much like the 1965 version it takes plenty of dialogue from, in this version, contrary to the original novel, a few guests have been lured in under pretenses that would turn out to be false the moment they reach the hotel; the General's friend is not there, there's no Hollywood producer for Ilona (plus Iranian colleagues for the Judge and friend for Lombard, but those can be attributed to just being thin lies). Yet nobody protests about the absence of those key figures or asks the staff their whereabouts; everyone is remarkably docile about blatant lies obvious from the beginning. The Martinos apparently were not even aware that the place was a huge hotel and are even surprised that there are 8 guests to service - quite expected in a hotel of that size, really - but they have been there for several days already.
