2002 Subaru WRX Wont get into gear!

I was driving back from the airport, I was in 5th gear and my rpms all of a sudden shot up so I slowed down and downshifted to 4th gear and it seemed to run fine so I spead up and shifted back up to 5th gear and the rpms shot up again so I slowed down again and downshifted to 4th gear and the rpms still shot up. I pulled off the road and stopped the car and thentried to accelerate and the car would just rev up but wouldn't move. The clutch seems to be fine but the handle will go into every gear without pressing down on the clutch pedal but the car still wont move.
I've been told that it could be the clutch, the transmission, or one of the two bushings.
What could be the problem with my car?