I just can't see Hastings being left out unless it's an injury or some kind of falling out, especially as no other specialist 10 has been named. Christie has been on the radar for a while and has been good for Sarries so don't see him as too much of a surprise to be honest. Ben White I had to Google. Toony loves a random scrum half.
It's a pretty young squad anyway. To be honest, I'm not sure I would have disposed of Maitland just yet, I'd still have him in there and I think that's a bit rough. I'm not convinced any of the other wingers apart from Duhan are better than him yet, and, while building for the WC is important, it's the 6 nations and I'd quite like us to win it one of these days!
ETA, just noticed Fraser Brown is out as well. Probably less of a surprise, but still a good experienced player. Would have probably had Kebble in as well.