Only in Apple Maps??
I thought this only happened with Apple Maps?
Hoover Dam Road.kmz
It's been like that for years in GE. They don't want to render the bridge in 3D, so they just have it "stuck" on the terrain. If it's a well known bridge, it generally has a 3D model built into the 3D buildings layer.
Also, you can occasionally find terrain errors, such as weird mountains that aren't there, or holes that shouldn't be there. There's a kml on GEC somewhere that lists them all, but I don't remember how to find it.