Continuity mistake: The first time we see the scene of Birdie sitting poolside waxing about her and Miles' fame, she brings her left hand up to hold down the side of her large hat, which obscures the camera from seeing Ms. Brand sitting down next to her, and when done speaking she pulls the hat down from the brim. When the scene is shown later a second time from Brand's point of view, when Birdie is talking she isn't holding the side of her hat, and takes it off from the top.
Continuity mistake: When Helen enters by mistake Derol's room, there's no smoke visible; she leaves, and in a tighter shot on him a blunt leaves a very conspicuous trail of smoke. (01:41:00)
Continuity mistake: When towards the end of the movie Miles from the top of the stairs shouts "What? You think you're an alligator?" Birdie and Whiskey are in a different position in their close-up. (02:08:30)
Continuity mistake: When Lionel says "Why the hell not?" at the unspoken understanding of starting to shatter statuettes, Claire next to him is standing clawing at her own fingers, while in the background a moment earlier her hands were higher and distant. (02:02:30)
Continuity mistake: When Blanc "offers some courage" to Helen, his hand in close-up is around the side of the glass, and it is above it at the cut. She accepts the glass, and her hand changes position on it at the next cut as well. (02:01:05)
Continuity mistake: When Helen shows in close-up Andi's napkin for the first time, look at the position of her finger, next to "Teaching." After a brief cutaway, it changes position. (01:57:05)
Continuity mistake: When Helen grabs the bottle of hot sauce from Blanc's hand, the label turned between shots and it begins in Blanc's right hand when he was just switching it to the left in the previous shot. (01:45:15)
Continuity mistake: When Blanc crouches by Helen telling her that "This is our cover", she is holding the diary with both hands, but in the previous shot her left hand was on the ground, and switches again back and forth. (01:45:10)
Continuity mistake: When at the restaurant Blanc says the anti-prophetic sentence "Miles Bron is not an idiot", his arms go from folded to unfolded and vice versa between shots. (01:19:25)
Continuity mistake: In the reveal of the crime that hasn't been committed yet, Blanc points at the table to show the trajectory of the dart. Claire suddenly stands from her seat, but she is back sitting properly a moment later. (00:48:05)
Continuity mistake: After Andi's mic-drop moment interrupting Miles ' speech, Claire runs after her. Birdie is biting her fingernail, with a different position in close-up (her other fingers are up in the wider angle, lowered to let you get a better view of Kate Hudson later). (00:36:25)
Continuity mistake: When Birdie makes her way poolside she smiles at Lionel; in her slo-mo approach her left hand holds the foulard, but in the next shot she is holding the brim of her hat. (00:27:50)
Continuity mistake: In the flashback, Helen tells Blanc as he kneels to tie the shoelace "Duke and Birdie, I think they're onto me." Notice the sunglasses poking from the top of the frame, and the right hand that moves away showing that the shades are in her left hand. But it cuts back on her in a shot from the waist up and her glasses are in the right hand. (01:25:35)
Continuity mistake: The night before the boat trip, Blanc tells Helen "This is your last chance to back out"; his forearm for just that shot is on the back of the bench. (01:24:55)
Continuity mistake: Andi topples the shelf and various books fall off scattering on the floor. In particular, "The Innovator's dilemma" is propped on top of a different open book. In the close-up where she pulls the napkin out of it, the book shifted without anyone touching them. (01:23:30)
Continuity mistake: When Helen shows Blanc the notepad where she drew the Clue-style tab, the letters are drawn in a different way from the close-ups (most obvious hint; the M for motive does not touch the grid). (01:24:20)
Continuity mistake: Debriefing Helen at the restaurant the night before the impostor game begins, Blanc tells her how to behave on the boat. Her hands are off/on the table between shots. (01:18:45)
Continuity mistake: At the beginning of the retelling of the story, Blanc holds Helen's phone in his right hand, and yet the close-ups are of a left hand. (01:13:40)
Continuity mistake: Throughout the conversation with Helen on Benoit Blanc's terrace, her facemask switches position between two distinct spots on the table. (01:11:00)
Continuity mistake: Blanc says "Where's Duke's phone?" holding his wrist in the closer angle, but his hands weren't there in the previous wider view. (01:04:05)
