1) If a player disconnects and then reconnects back to the game you can no longer see the gold values of the units or upgrades, nor can you properly see where the units are being placed when building them as you just see a small square in terms of where the unit will be placed instead of viewing the entire unit. Also the tier list doesn't work afterwards. This is extremely frustrating and makes the game unplayable after a disconnect.
2) Whenever you are clicking multiple similar units to mass upgrade them there are occasions where spamming the upgrade key (say "X") to mass upgrade them deselects the units and selects back the builder prompting him to build a unit based on the key pressed. This is extremely annoying. Make the unit selection being sticky and only when clicking to something else removing the selection. In cases where you want to mass build units and upgrade them fast makes the game unplayable causing you to not spend all your gold and lose a wave.