Plot hole: Benoit Blanc ruins on purpose the murder dinner party because, allegedly, someone is really trying to kill Miles, and he wants to warn him that it's not a game. But as we know later, Blanc is actually trying to investigate the murder of Andi Brand and he does not really think that Miles Bron is in danger. In fact he is positively convinced that everyone has motives to kill in order to protect Miles and all he wants to be on the island for is to gather clues and investigate. Cutting the game short does not serve his purpose at all, in fact it defeats it. Had he played along, both Helen and him would have had a perfect excuse to investigate. In fact it is a miracle that nobody went back to their rooms right away after that tense moment, instead of being busy with the opening investigation; you even see that they are groaning and complaining and want to leave. The movie explains away most of the other details but none about this.
Suggested correction: Blanc knew he couldn't hide Helen's identity for long. He said so at 1:15:15. His fear was justified when Duke discovered Helen's identity on the night of her arrival. In short, Blanc and Helen were on a clock.
Regardless of how little time they had left (Blanc estimated "another week", so the leak happens presumably earlier than he anticipated), ruining the dinner does not serve the purpose; gives "Andi" less time to search the rooms, which is what Blanc planned her to do.
If the game was allowed to proceed, Helen would have been forced to play along. Any behavior, other than playing along, would have been suspicious.
Plot hole: The puzzle box that Miles sends to his friends opens and closes on its own, but its hinges are not connected to any electromotors or kinetic mechanism.
Plot hole: The Distruptors show up at Andi's house right after the killer (Duke literally crosses paths with him) and are enraged and desperate because they can't find her. At the same time, Andi is dying from apparent suicide breathing the fumes of her car. It'd be pretty extraordinary if they were snooping around her property banging at her door and being dumbfounded for, as Claire said, one full hour, but didn't hear a car running in the garage of her small house. (01:32:25)
Plot hole: There is a pivotal moment when Duke poolside casually says; "remember that night when..." That is a mighty strange way for him to mention the very last time the two met, barely two weeks earlier. Miles was not even supposed to be in the country, but Duke, who later jumps straight to casual blackmail once he gets the Google alert about Andi, never mentions that to Miles before or since. Miles cut him off pretending he meant "Anderson Cooper", but for the rest of the movie he struggles and has no leverage on Miles to the point that he pimps his girlfriend out to him. Furthermore, he mentioned the "pancaking" to the other friends, but somehow never mentioned it was Miles. If he was not going to take advantage of that, then he had no reason at all to keep the secret, especially with the lot of them hanging out for an hour waiting at Andi's door. Anyone would have mentioned the fact already back then, or if they realised it was important, would have already started to use it.
Suggested correction: When Duke says "remember that night," he doesn't know that Andi is dead. At this point, he thinks Miles went to Andi's house (just as they all did) and didn't go in. Miles has reason to cut him short, though. Attempted murder is also a crime.
I can't stress enough how absurd it is that he'd tell his friends and co-conspirators that he nearly had an accident without mentioning WHO with. They are banging at the door of Andi without a clue for ages, over a matter that has Miles at the center of everything. That's not how human interactions work. They all are outside her house, and he does not mention the identity of the person responsible for the accident? Again, one could only withhold information like this if there is a purpose.
Feel free to file this one under another mistake entry.
Plot hole: In the flashback, Whiskey fired the speargun at Helen at the bungalow away from the main house as she was fleeing at the beginning of the blackout. She has no light source with her, but somehow in the earlier showing of the events she was one of the first people to pop up at the party room seconds after the blackout started, and with a loaded speargun. (01:06:00)
Plot hole: Helen looks at her phone for the first time at 9:58. From there, she quickly browses the messages everyone has been sending for several minutes to her, and does a google search. Since she gets interrupted by Whiskey and then this interruption is further interrupted by the hourly 'Dong', she must have ransacked Duke's apartment in barely a minute, which is impossibly fast. (01:41:20)
Plot hole: It's an established fact that the culprit is an idiot (actual quote), but still, not a COMPLETE idiot. Some things such as keeping the envelope as some sort of trophy are in line with the hubris of villains, but there's absolutely no reason at all why he would still have in the back pocket of his pants Duke's phone after having a ton of time to get rid of it (he got rid of the gun and a pair of gloves he had the time to go look for in the dark too), especially in a spot so visible and being known for not owning any phone himself. (01:53:40)
