RandV
It's a wolf v2.0
That's what I was thinking unless they got away for a while and assumed another Star Destroyer picked them up. Anyways, I don't think she should have been at the battle, all signs in ANH point to her just receiving the plans. Again I would have had the plans transmitting to her a bit away from the battle, she gets going - light speed fails or something and boom a ANH. It bothers me that nobody producing the movie thinks about the beginning of ANH here.
So the other option is a bit of time passed and they caught up with her. She didn't know Vader had slaughtered a bunch of people which is strange because they were running the Death Star plans relay to get them to her.
Another Star Destroyer that Darth Vader just happened to be on as well?
But yes while they did a good job of closing the 'critical design flaw' loophole they did a poor job in the transition period, as Leia's "diplomatic" vessel was literally at the scene of a major battle and the universe doesn't have the technology to track your destination once you hit light speed.
Though of course the original movie kind of messes this up too, as if she had these critical Death Star plans on board why didn't she deliver them straight to Yavin, and then go find Obi Wan.