I believe to have found 2 minor bugs:
1) while upgrading a T1 mex to T2 the resulting T2 is created at the start of the upgrade (if you shift select the upgrading T1 mex you can see both units), this gets in the way on the "select lovest tech idle mex" hotkey. This doesn't seem to happen for T3 mex. This bug also applies to the first upgrade of the hive, ED-3 shield upgrading to ED-4 and T1 factories upgrading to HQs.
2) The reclaim left by an upgraded kennel il 400 which doesn't take into account the cost of the base structure (ie: a hive will leave 285, 570, 850 reclaim depending on how much was upgraded, a kennel leaves 450 is unupgraded and 400 if upgraded).