I'm pretty sure that anything will penetrate the rear armor 100% of the time. Just sayin, that's a pretty glaring weakness.
Plus, soviet mines should be everywhere.
Those are hardly glaring weaknesses. Everything is vulnerable to mines, but they are hardly reliable, especially with the panzerwerfer in the same building , they don't last long where you need them most and unless the german player is making a mistake attacking the rear on the fastest tank in the game is not an easy task. In fact, this is a weakness of all tanks and the panther being the faster and having blitz can exploit this far easier then the soviets can to it.
For comparison, the tiger while it is even more durable and has more offensive power is rather slow. So SU-85's and AT guns have more time to turn and attack before being flanked and is more likely to be hit by artillery due to size. The panther suffers from none of this.
The panther SHOULD be vulnerable to AT infantry, but we all know that such a thing doesn't really exist for the soviets.