Kenzo complains that he's being taken along to the stealth ship to be a "canary in a coal mine". His helmet-camera feed is in fact labeled as "CANARY" on Alex's station.
For Earth surface navigation you only need degrees of longitude and latitude. Belter navigation would be much more complicated. You would need: distance from the sun; distance above or below the ecliptic; position on a line between the sun and some distant star; orbital vectors of speed and direction (defining direction would also require multiple points of reference). And you need that info for both the vehicle and its destination. In the belt, everything is always changing relative position with everything else.
This is the first time the original owner of Joe Miller's hat he wore on Ceres is revealed as Inspector Sematimba on Eros.
Eros is the Greek god of love. In the Roman pantheon called cupid. In Greek there are four different kinds of affection/love, each with its own name. Eros being the sexual love between a man and a woman. It's where we get the word "erotic" from.