A minor issue, but when you have storage limits enforced, and you can finish a mission with too many items AND too many live aliens. In OXCE the forced item sale comes first, then the live alien sale. It's possible for the player to have sold enough aliens during the item sale, but the live alien sale will come up anyway, even when no longer necessary.
This once confused me and led me to sell more aliens that I didn't need to sell, since it was a "forced sale" so I figured I had to. After retesting I now realize I could have just hit "sell", but still.
In regular OXC the Alien sale comes first, which prevents any confusion. That would be one way to solve it.
If there's a reason OXCE departed from that, another way - indeed, probably more convenient for the player - would be to delay the alien overflow check until after the item sale screen.