Seeing as BD went through alot of testing, I'm sure they got rid of all the very obvious bugs. Do you really think that a tester, who's job it is to play this game hours and hours a day, wouldn't notice something like all the monsters dissapearing in the second battlefields? I mean... these guys aren't dumb. They would have noticed.
So I'm guessing something went wrong at the last minute. (Copy protect, anyone?)
Well We dont even know if they tested battlefields, They might have only tested the main campaign, as most bugs and errors show up in the BF's.
But outside battlefields the bugs are minimal, most complaints I have are with design decisions not beta testers.