Trivia: K Callan, who plays Christopher Plummer's mother in this film, is actually six years younger than Plummer in real life.
Trivia: At the end, Benoit Blanc says he noticed the blood on Marta's shoe the first time she stepped in front of him. Rewatching the sequence when they first meet, as he says "I've been doin' a little pokin'" he does indeed look down as he speaks and takes a fraction of a second pause, noticing the blood but continuing to talk as normal. (00:23:45)
Trivia: Michael Shannon has played Jaeden Martell's father twice on screen, in this movie and Midnight Special.
Trivia: Jacob Thrombey, the far-right troll, was based in part on the backlash and targeting that Rian Johnson experienced after The Last Jedi was received unfavourably by some people. He's stated it's a broader commentary on the state of social media, not about his Star Wars experience specifically. "It doesn't matter if you made a Star Wars movie or if you have a cooking YouTube channel, or you collect books on the internet, someone's gonna be yelling at you on the internet."
Trivia: Joseph Gordon-Levitt cameos, at least his voice - he's heard on the TV show Marta's sister is watching. He's a frequent collaborator with director Rian Johnson.
Answer: To add slightly to the other answer, evidently some of the blood in the scene had to be digitally removed for the film to secure a PG-13 rating, which explains why we don't see any actual spray/gush. But we are to assume that a drop managed to splash onto her shoe when he slit his throat.
TedStixon