When I use two pistons to push a rail and the block supporting it in perpendicular directions at the same time, the rail drops as an item (whether it's being pushed onto a solid block or not) but remains visible and partly functional as a block. It carries minecarts if there's a solid block under it. It blocks existing water if the block it displaced was doing so. It extinguishes fires and destroys crops. And it can be pushed by additional pistons.

This must be a glitch, because the fake rails disappear (without dropping anything) whenever the game is saved and reloaded, or they are broken, or they gain or lose redstone power (even if they aren't Powered Rails).