Nero and crew being on Rhura Pente for 25 years, but the ship just happened to still be there when it was time to break out
Actually, Uhura wasn't very specific.
I was tracking solar systems and I picked up an emergency transmission from a Klingon prison planet. A Klingon armada was destroyed, 47 ships.
That's ALL we got.
It's perfectly conceivable that Narada was being held in a remote research facility, but the Klingons never figured out how to dismantle it, or even take control of its systems. According to non-canon source, "Star Trek: Countdown", the ship was retrofitted with some reverse-engineered 24th century Borg technology which made it adaptable and impregnable.
Nero could have escaped, spent quite a bit of time looking for it, then steal it back and use it to free his comrades from Rura Penthe.
There's a fuckton of retarded shit in this movie, but the fans' capacity to overblow things never ceases to amaze.