My apologies if this has been brought up before, but it just occurred to me: why didn't the Borg create the temporal vortex in their own galaxy, thereby precluding any possibility that they would be interfered with?
I'm assuming they traveled from the Delta Quadrant. Couldn't they have just made the same journey...but in 2063? If they had done this, wouldn't this have assured they met no resistance when entering Earth's orbit?
At the very least if the Bog were going to break off of their plan by abandoning an attack on the "modern" Earth of the TNG days, they could have at least waited until they had flown back towards the Delta and then pulled their time travelling stunt once they were out of view of the Federation. Its a flaw some of us have been pointing out since the far away days of the ST AOL forums.
Of course VOY made it worse by giving us a glimpse of the hundreds of cubes the Borg appeared to have at their disposal. So why send one to attack Earth? Especially considering it carried a very important piece, albeit contrived, cargo in the form of The Queen.