Ransom ghostwrote some of Harlan's books and was bribed by Harlan to keep quiet about it.
- Ransom's murder-related knowledge is justified by him having been Harlan's research assistant for a summer, but it's a bit of a stretch to think that he would be able to employ it in his murder plot as well as he did if he wasn't able to think like a mystery writer.
- Harlan wasn't just doting on his black sheep grandson, he was paying off his ghostwriter.
- One major point of Ransom's characterization is that Harlan saw a lot of himself in him. It's possible that their writing styles were similar enough that Ransom's writing could pass as his grandfather's.
- It would also give Ransom a stronger motive than just wanting to frame Marta and get the inheritance he feels he's entitled to, but that's more of a writing nitpick.
- Since Harlan's stated motivation with regards to the inheritance was to enable his family to develop their own independence and forge their own paths rather than simply rely on his name and fortune, had this been the case it would almost certainly have come up at some point. Perhaps more likely is that this is simply the filmmakers implying that Ransom, like his grandfather, could have had the makings of a pretty good mystery writer had he not been turned into such a spoiled, feckless little shit by leeching off Harlan's wealth instead of developing his own talents.
Harlan orchestrated the entire plot, including and especially his own murder.
- There are plenty of hints that Harlan knew he was going to die that night and had made plans for it.
- He announces to Marta that he's 85 years old and ready to die, as if comforting her in advance for what's about to happen.
- He wrote a new will just one week earlier.
- He cut off his entire family in one fell swoop that day, preparing them for being legally cut off in his will.
- The only family member he told about Marta being his sole heiress was Ransom. He mentions at another point that Ransom most reminds him of himself, but that he's also a cruel, selfish person i.e. the sort of man smart enough to launch a convoluted murder plot to incriminate Marta and morally bankrupt enough to follow through with it.
- Despite being told the symptoms and timeline of morphine overdose (and presumably knowing them already, as a murder mystery novelist) he doesn't notice/mention that four minutes after the injection he's experiencing none of the symptoms.
- The fact that he rattles off his instructions to Marta so quickly in the face of his supposed impending death means either he at some point invented plans to escape his own house and fake an alibi for countless random scenarios, he is the world's greatest improviser, or he knew this would happen ahead of time and planned for it.
- If Harlan was taking morphine (apparently on a nightly basis), he must have been in considerable chronic pain. Not surprising that he would be considering a way out.
Benoit Blanc's accent really isn't what he usesPerhaps Blanc is a foreign agent assigned to work in the United States and to "fit in" he thought of the most stereotypical and exaggerated southern accent he could think of, especially since everyone around him seems to realize he's faking his voice.
Marta will join Blanc in investigating future mysteriesNot only was he impressed with her quick thinking and kind heart, but the two of them are able to come to conclusions about the case at around the same pace. Blanc would surely love to take her on as an apprentice.
The sequel will be kick-started by a stolen heirloom/artifact rather than a killing, and will be a pastiche/dissection of Maltese Falcon-style mysteries in the same way the first was for classic Murder mysteries.
Rather than direct sequels, Johnson may opt to have Blanc (and possibly the cops) be a recurring character in future filmsThat would strengthen the similarity to Poirot, whose mysteries aren't necessarily sequels to one another and can stand on their own.
- And maybe one of those direct sequels could tie into The Brothers Bloom, with Blanc finding Bloom and Penelope because one of Bloom and Stephen's past cons ties into a case he's working (Blanc certainly seems like he'd fit into the world presented in The Brothers Bloom, and it would be nice to see how Bloom and Penelope is doing since the end of their story).
- Confirmed! Rian Johnson has said that Benoit Blanc will return in future films.
There could be a tie-in/spin-off series of books detailing Blanc's earlier career
Harlan is a Canadian who is in the US illegally
- Not impossible, but exceptionally talented people, which Harlan certainly is, do get visas very easily.
Ransom will get off scot-freeRansom still has excellent lawyers, and they could pass off his confession and attack on Marta as being pure emotion and unreliable evidence.
- Marta likely wouldn't stand for that, so I expect she'd use her newly acquired wealth to help fund the case against Ransom. The family will likely also testify against Ransom, which means even his own parents wouldn't vouch for him. Plus, Blanc would certainly have some clout, being a famous crime solver. Not to mention Elliott and Wagner. Plus, Ransom wasn't just accused of causing Harlan's death; not only is there nobody else to pin Fran's murder on, Ransom already confessed to it. A slightly less harsh sentence is possible, but "scot free" is a huge stretch. Plus, that would invalidate so much of the story.
Harlan plotted out Marta's escape in advance because he had already accepted that at least one of his family would try to murder him.
- His insistence on wanting to "close the book with a flourish" speaks to a dissatisfaction with his state of being - seeing potential death at every turn, unsure which of his children to trust.
Marta is half faerie
- Marta's most unique trait is that she vomits when speaking deliberate untruths, but we see that she can get around that effect with Exact Words. Now, one of the near-universal rules for Fae is that they Cannot Tell a Lie, but can use Exact Words to speak misleading truths. Being partially human might let Marta lie, but her Fae half rebels against it and makes her physically ill.
- It's a recurring plot arc that nobody knows Marta's exact ancestry, and we never see her father.
The sequel will reunite Rian Johnson with some of the cast from The Last Jedi, The Brothers Bloom, Brick, and Looper
- In a form of Ascended Extra, Joseph Gordon-Levitt will go from being a voice cameo to playing an actual character in the story.
- Lukas Haas will play a man accused of murder in a Casting Gag.
- Rian would probably love to work with Kelly Marie Tran again.
- John Boyega would be a welcome addition as well.
- It'd be a crime to not consider Rinko Kikuchi.
Knives Out is Marta's first book, adapted for the big screenSince she legally owns the stories, Marta is now free to give out the movie rights. Out of respect for Harlan, she left his works alone, but decided to write her own stories... starting with the insane series of events that landed her the inheritance in the first place.