The "spending units" visual is underwhelming and doesn't change to reflect the amount spent.
The Horizon condos store isn't very prominent.
The posters in Hospital are very boring to read. (compared to, let's say, Subway's)
This luxurious Tower resort thingie has a very limited selection of foods and beverages.
Casino's "winning units" effect includes coins and gems. Nowhere else in the game are gems used to represent currency.
Most of the casino's machines have no slots for inserting money, some even lack ones for dispensing it.
And my biggest and at the same time tiniest nitpick...
THE PHYSICAL REPRESENTATION OF UNITS ISN'T CONSISTENT AT ALL
First of, you have the bills item. I have no problem with it, as it's the only instance of bill-based units and so is consistent with itself (weeeell, except the tiny images on the vending machines).
Then you have all the different unit coin designs. The one in Treasure cove, the one in the "spending units" and "winning units" effects, the one that physically dispenses from some of the casino's machines, the one in the Treasure chest o' units item, the one in the Bag o' units item, and possibly the one in the Pile o' units item (haven't seen that one yet).
As someone who's into everything currency and token-based, this triggers me greatly.