On page 3, Simon is wearing the same glasses he wore in "Serenity". Here it's revealed they are special glasses that prevent his retinas from being scanned by sensors in the environment.

In what I presume is a printing error in panel 3 of page 3, the painting in the background has a strange double image on it. On page 2, the same painting does not have that double-image look.

For their art heist, the crew is using a truck with the logo of Xpresscargo on it. This must be a delivery service in the Verse.

On page 6, panel 1, there appear to be several Firefly-class ships among the many in the air above the city.

On page 9, we get the first appearance of Serenity's new Mule, a larger antigravity vehicle this time. The old Mule was damaged, possibly beyond repair, in "War Stories".

On page 11, panel 2, the military-industrial salesman appears to have identified Mal, probably in an Alliance database, based on the video feed from the remote attack drone; notice the picture that comes up on his screen shows Mal in his usual brown outfit, not the Xpresscargo coveralls he's wearing for the current heist.

This issue reveals the existence of a former terrorist group called the Dust Devils made up of Independents who target people and places aligned with the Alliance. 

On page 19, panel 2, there are, impossibly, stars shining through the dark portion of the two crescent moons in the sky! Funnier still is that when I scanned this panel to point out the moon error, the scan revealed that the letters BWS are written all over the starfield background! BWS is an instruction to the colorist to put in black-with-stars; it appears both the colorist and editor missed it during proofing and the instruction got left in the finished art. Also, if you use Google Images with the term "stars", one of the first results is the same star pattern, from Wikipedia!
From Better Days	From Wikipedia

On page 20, the crew lifts the Buddha statue straight up by a rope. But the statue would not rise at a perfectly even keel as it's shown here with just one rope supporting it, it would be tilted forward by it's uneven distribution of mass.

On page 21, the Buddhist monk recognizes Jayne, by his face and the giving of money, as the hero of Canton. This is a reference to "Jaynestown", in which it's revealed that Jayne is considered a hero in the town of Canton on Higgins' Moon for stealing money from the rich industrialists and giving it to the poor.