Rook and knight used together within the same move - legal? This is my first question on chess beta and I don't know if I'm insane or if the cpu is broken. So I was playing chess against a CPU on the iPhone with the app 3D Chess Game, and the CPU (playing black) made an odd move. 

Black to move:



White to move (one move later):



I obviously edited this to simplify it, but the basic idea is same. That is:

Black moves Rook on a8 to d8 and Knight on g8 to f6 in the same move.

Is this legal? Or is it just a bug in the system?
That's either a bug or some non standard chess variant