Mei's backpack has a hologram of two dinosaurs named Misko and Marisko. In The Expanse books, Misko and Marisko are the two main characters in a popular animated show. When Miller and Holden are trying to escape from Eros Station in the first book (Leviathan Wakes), they both reminisce about watching the show as kids.
13m 41s in to episode 11 of season 2 a map of Ganymede station is shown. The map actually is that of Great Britain. That is definitely the outline of Wales on the the left hand side of the screen. Particularly apt given the title of this episode.
The Martian destroyer that is shadowing the UNS Arboghast on Venus has a nameplate reading "SHANDIAN" in Roman script. "Shandian" means "lightning" in Chinese. It's hard to be certain, but right after the Roman letters there is a small design that looks like "Shandian" in Chinese characters.
When Martens is dressing down Bobbie back in the Martian Embassy quarters (4:56), he reminds her about the story of Bobbie climbing with her father on Olympus Mons; that backstory is likely derived from Kim Stanley Robinson's 1985 novella Green Mars.