History Foreshadowing / GlassOnion

* When Peg goes to Miles and outright BEGS him not to have Birdie make the statement revealing she [[spoiler:stupidly, unknowingly allowed the use of a sweatshop in one of her ventures]] because that would not only ruin Birdie, but Peg, herself, due to most of her resume being working for Birdie, Miles gives her the brush off and a smile as he asks her to get Birdie to make the statement. This foreshadows two big indicators of Miles: 1) he doesn't give a damn about anyone but himself, not even to offer Peg words of encouragement (such as, "Birdie told me how much you help her and do for her. You'll bounce back after this is all over") and 2: he adamantly believes his natural charisma (which he DOES have despite being an idiot) is more enough to get people to agree to whatever he asks of them.

** The individual puzzles are not deductive or logic puzzles, but simply a series of references the person solving it is expected to recognize. They do not test the participant's intelligence (or even testify to Miles' intelligence), but rather simply what bits of info or trivia they are familiar with (Do you know what a stereogram is? A compass? A memetic chess match? What a fugue is?), This foreshadows the mystery and the titular Glass Onion metaphor - [[spoiler:There's no mystery, the answer is right there]].

** The line also sets up the other twists of the movie: [[spoiler:the puzzles might be not as impressive, but the way Blanc is dismissive of them is at odds with the more cordial attitude he is showing in the scene. That's because he didn't actually solve them or even see them properly, he only saw the pieces left, which included bright shapes and a TabletopGame/TicTacToe set, leading to his assumption. The fact that Miles doesn't contest the statement, nor seems irritated by it (which contrasts his reaction to Blanc spoiling the murder mystery) shows that not only did he not make the boxes, he didn't even bother checking them. Not only he isn't as clever as he paints himself to be, he doesn't even properly follow through on his own ideas.]]

* After Miles welcomes everyone to the island, Blanc and Andi are left alone on the beach. The first line that Andi says to Blanc is "This rich people shit is weird." [[spoiler: This is because Helen isn't the rich CEO Cassandra Brand -- she's a humble schoolteacher -- and she expresses familiarity with Blanc because they already know each other.]]

** The film shows Miles and Duke sitting down and [[spoiler:Miles placing Duke's drink into his hand]], which will later be proven as [[spoiler:the way Miles pushed a tampered drink onto Duke.]] The film tries to make the viewer doubt by providing an explanation where the visual depiction changes to show [[spoiler: Duke picking up the glass mistakenly from the table]], but viewers paying attention to the guys the first time, and not to Birdie twirling in her dress like [[spoiler:Miles asked everyone to watch]], will see that the second version of events is inconsistent and a lie.

* Yo-Yo Ma cameos to explain the musical puzzle in the box as a fugue, a tune which changes and forms a different composition when layered over itself. This foreshadows the film's unusual structure-- [[spoiler: the film flashes back to reveal a massive plot twist, initiating a replay of the film, the "same tune", but with the events completely reframed by the new information and point of view, and making a very different bigger picture.]]

** After [[spoiler:Andi is shot]], Blanc runs up to her and [[spoiler:openly calls her "Helen", the meaning of which is imminently revealed upon the approaching plot-twist replay.]] In the chaos of the scene, this detail is very easy to miss.

** When Duke starts to confront Miles about a deal after getting a phone alert, [[spoiler:a brief flash of the phone screen toward the camera shows a photo identifiable as a portrait of Cassandra Brand, showing early on that Duke had received an alert to Andi's obituary, but keeping this from being obvious through the phone screen being far from the camera and briefly shown.]]

** Some shots in the film show [[spoiler:Miles with Duke's phone, and Miles with the gun and then stashing it away in an ice bucket]], but the framing and action is designed to keep those put of notice.

* When [[spoiler:Helen disguised as her twin sister Andi]] arrives at the dock to get on the boat to Miles' island, all the Disruptors are staring at her in confusion and disbelief. Blanc, however, is ignoring her and carefully watching them with an intense expression on his face. This foreshadows the revelation later in the story that [[spoiler:he's working with Helen to uncover which of the Disruptors murdered Andi, and he wants to see their reactions because he knows one of them thinks Andi is dead.]]