Trivia: Warwick Davis plays one of the marauders. He also played Wicket the Ewok in Return of the Jedi.
Trivia: Pom Klementieff, who plays Mantis in the Guardians of the Galaxy films, also directed by James Gunn, has a cameo here as one of the patrons inside the club on Corto Maltese.
Trivia: Stan Lee makes his usual cameo, this time as a patient at the asylum where Selvig is being held.
Trivia: The Anabelle doll from The Conjuring, another film of director James Wan, is visible while Mera is taking Arthur to her submarine ship. Blurry but there.
Trivia: In Cloud City, when Chewy finds C-3PO in pieces in what looks like a droid scrap room, you can see what looks like the upper half of IG-88 leaning up against the wall. It is revealed later in books to be the IG-88 unit that went in search of Han, but was intercepted and destroyed by Bobba Fett.
Trivia: At the end of the film when Scrooge is going round being nice to everyone, as he's on his way to the Cratchit's house, we see in the background a shop called "Micklewhite's". This is Michael Caine's real surname. (01:20:55)
Trivia: When Keith Richards is looking up the rule in the pirate code book, the skull ring on his finger is not a prop; he has worn it since receiving it for his birthday in 1978 from a famous London goldsmith, who used a real skull when modelling the design.
Trivia: During the big fight between Batman and Superman, a broken window has the same shape as Ontario, in Canada. Superman creator Joel Shuster was born in Toronto. The broken window is only ever shown from Superman's angle, not Batman's. This was confirmed by Zack Snyder as being a deliberate, if obscure, easter egg.
Trivia: There is a scene where Hercules is being painted on the side of a vase or something. Hercules is wearing a lion skin - when he throws the lion skin down, if you look carefully, you can see that the lion skin is made out of Scar, from The Lion King . (00:55:20)
Trivia: Steven Spielberg has a cameo as one of the doctors when Elliot and E.T. are 'hospitalized' inside the house.
Trivia: In the open-matte print, right after the credits, the support beams of the movie lot walls are visible, painted in blue to simulate the sky. In the theatrical version and the current Disney+ streaming movie's original aspect ratio (bottom picture), one can still see the beams for a split second after the postman puts the letter in the mailbox (though there's no way here to identify them as lot walls).
Trivia: In the scene of Missy's funeral, Stephen King plays the priest.