They know fans will be spying on the studio once production begins. We live in an era where drones are flown over the outdoor sets. The cat would be out of the bag the moment Mark or Billy Dee are spotted anywhere in England next month anyway.
Yeah, which is why the Carrie news is the bigger surprise to me. They could have kept that under wraps until opening day.
Perhaps they just wanted to get in front of viewers and make clear it’s unreleased footage, not CGI (I guess they only have themselves to blame for any assumptions about the latter).