Why was Spock spit out from a different white hole (the theoretical other end of the black hole)? Shouldn't there have been a white hole travelling through the galaxy for 25 years and longer?
The black holes in the film didn't have much in common with real ones. The film black hole acted much more like a cross between an unstable wormhole, opening up in random places, and that time vortex from VOY: "Future's End", where a few seconds on one side is equates to several years on the other.
Unlike the concept art, the thing that spat Spock out clearly wasn't white.