A white bunny-like alien looking figure was sighted on set during filming. There are fans who think this may be Meep the Beep, a cute looking though vicious alien from a Doctor Who comic, but this hasn’t been verified. If true though, it means Davies would be adapting a comic book story for at least part of the 60th, which would be a first for the show. There’s another bug like alien sighted on set as well that some think may be Wrath Warriors, also from the comics, also unverified
Doctor Who Wiki on Meep https://tardis.fandom.com/wiki/Beep