The biggest plothole being, if they had time travel technology, then why not go back in time FIRST and THEN travel to the Alpha Quadrant?
They didn't even have to go back very far, just to any time before "Q Who?" was set.
Back in the era known as the 90s on the ol' AOL Trek boards I mentioned this point and several others from the film that simply made no sense. Its too flawed a movie and too uneven for it to be considered a great flick.