This was my favorite of this series of specials. I was pretty concerned that they had cast NPH as The Master for a bit there (I'm a NuWho Noob, so I had never heard of The Toymaker), but aside from that, it was pretty good! Ended up skipping through the song-and-dance number, though. Just wasn't for me. Intrigued by the bi-generation twist and the new generation. We got too little of 15 to really develop any sort of insight, but he seems solid enough so far. Looking forward to Christmas!
Also, where the hell did that hand come from at the end? It came from off the edge of the platform. Was it a POV shot? So confusing XD
The hand I think was a callback to Last Of The Time Lords where a hand with red nail polish retrieved the Master's ring after he died to bring him back to life. The Toymaker mentioned that he beat the Master and trapped him in his gold tooth, so this is some sort of Master shenanigans I think.
Definitely a call back, but my question is more so the physicality of it in universe. That was the edge of a platform 50 some stories in the air, and the hand came from off the platform. Was it someone reaching through a hole in reality? An invisible floating entity that still cares about their nails? I'm very curious!