Alt-clicking an allied hero's health/HP bar incorrectly causes your player to say: "I have XX%HP YY% Mana". It says "I" rather than saying the name of the allied hero whose health bar you are clicking but the values are correctly displaying as the allied hero's HP/Mana.

The same issue applies to Alt-clicking the courier's backpack or inventory items. Alt-clicking the courier's items will cause you to chat that you have that item ready, even if your hero does not have that item. For example, If I select the courier to view its inventory and Alt-click another player's Vanguard being carried by the courier, it will chat: "[My_Player_Name]:Vanguard > Ready" even though my hero does not have a Vanguard. The same issue applies to:

Alt-clicking items in the stash will incorrectly say that item is "In Backpack"
Alt-clicking items on allied heroes will incorrectly say that item is "Ready" or "In Backpack".