You may recognize Bruno Verdoni (Carlos Davila) from his guest-star appearance on Syfy's Being Human (as Reverend Herring).
The Nauvoo, the massive ship being constructed by Fred Johnson and his team, has the most powerful sensor and communication array ever built. Johnson used it to spy on what was happening during the Donnager battle.
Uncle Mateo removes a malfunctioning sensor wire in his helmet. He lifts his visor, exposing his face to the vacuum of space. He then exhales slowly to prevent embolism, then re-locks his visor and finally inhales.
Tig Fong (Kaipo) has made guest appearances on Syfy's Dark Matter, Lost Girl and Warehouse 13 and performed stunts in 12 Monkeys, Continuum, Alphas and Helix. He was also the stunt rigger on Poltergeist (2015), co-starring Jared Harris.
Alex Karzis (Uncle Mateo) has made guest appearances on Syfy's Lost Girl, Warehouse 13, The Dresden Files and Mutant X.
Uncle Mateo's ship is called the Xinglong. It's described in the script as "a crappy two-person ship that looks like a Winnebago."
Coincidentally, Caleb Olivieri (Daniel) is also the co-writer, co-producer and location manager of a short film called Mars Is Laughing at Us (2014).
The story of the conflict between the Scipio Africanus and the Xinglong grew out of a single paragraph in the original book. The Belters starting to use rocks as weapons is exactly what Chrisjen is afraid of, as she mentioned on the roof of her house in Episode 4.
The Sopranos fans will recognize Lola Glaudini from her role as Agent Deborah Ciccolella.