Revealing mistake: The very first shot of the movie, supposedly of Anya Taylor-Joy lighting a cigarette, does not match the following shot on the pier; the cigarette appears to be black and with a brand sleeve instead of the normal one she is smoking. The background confusingly looks more like an interior than the pier she is standing on, and the lighter is a common Bic-style one instead of the Zippo she is using also later in the movie. That's because it's actually stock footage. You can literally find the clip yourself on Shutterstock and similar websites, by the description "Close-up of the silhouette of a woman's face sticking a cigarette into her lips, igniting her with a lighter, and exhaling smoke. The grim concept of the harm of smoking in a low key." (00:01:00)
Continuity mistake: During appetizers, John Leguizamo's assistant puts her work phone on the table to let him know she is resigning. Leguizamo is holding his glass when the camera is behind him, and a spoon when he's seen from the front. (00:13:10)
Continuity mistake: During the fourth course, after the gunshot happens, all the blood on the floor and kitchen bench disappears when the plates are about to be served. (00:42:12)
Suggested correction: This is simply because they very quickly and effectively clean the kitchen bench off-camera. That is why the man was standing on a sheet and they covered the open kitchen with a screen to catch the blood spatter. The blood on the counter was minimal and there was hardly any blood on the floor.
Other mistake: During the dinner Slowik reveals that his restaurant does not have nor serve bread of any kind. Towards the end of the movie Margot requests that he make her a cheeseburger, which he does. Where did the buns come from?
Suggested correction: This mistake completely misses the point. The chef NEVER says they don't have or serve bread; merely that the guests will not be getting bread as part of his meal plan. The movie actually makes a point of repeatedly mentioning the fact that the restaurant is known for its high-quality bread and even shows us a plate of their bread for a few seconds. They have bread... chef is just messing with the customers by refusing to give them any with a pretentious justification.
Suggested correction: He didn't say they didn't have bread. He stated THEY wouldn't get bread for that evening, since it's a common man's staple, and they are not the common man. So, they get a breadless bread plate with nothing but dipping sauces.