Headscratchers / Stanley and Stella in: Breaking the Ice

• How does gravity work in the sphere, and what is it full of?
  • The first part is internally consistent, being that fish have water ^note The distortions that water would provide isn't there, but hey, it's CGI from 1987 and birds have air, separated by ice. The orientation of the animals and the fact that Stanley can land on the ice proves there is some form of Artificial Gravity.
  • However, when Stanley breaks the ice, physics is thrown into the wind. Stanley slowly floats down as if he was in water, yet no water surface is visible where the ice was (or anywhere). After that, it's either birds flying in water or fish swimming in air. Worse off, Stanley floats and birds fly in the same frame, though this could just be a case of Stationary Wings.