Hi,

Crazy theory maybe but...could the hand coming out the picture in the 50th episode was that of Missy?

I know people have said it was Clara, but it would fit in with the weird camera angle on it and explain how The Master got out.

It was Clara's hand, wore Clara's rings / jewellery, and the weird angle was due to the 3D effects.

As to explaining how the Master came back - well the Peter Davison era always managed with a simple "So you did escape from... Castrovalva / Xeriphas / delete as appropriate." I can see no reason why such a line wouldn't suffice now.