http://bugs.winehq.org/show_bug.cgi?id=10281
--- Comment #6 from Jonathan echidnaman@gmail.com 2007-11-04 12:08:31 --- The more that I look at the occurrence of the bug, the more sure I am that it's a 2D layer getting in the way of the 3D models.
Sonic Rush, for example, uses 3D models inside it's 2D sidescroller gameplay. In gameplay, one cannot see the 3D model for Sonic the Hedgehog.
The boss stages are rendered in full 3D, however. (You still are sidescrolling, using the same 3D models for Sonic) In these boss stages, so have an off in the distant sky and forest instead of a straight 2D background.
And yes, I tested this in Windows and this is a Wine discrepancy.