...there's a gamebreaking glitch that can be observed on any given playthrough of the game, and it wasn't ever fixed because of lack of testing.
GameFAQs' daily top 10 lists are usually a complete joke, but sometimes you learn something interesting from them. For instance, did you know that in a two-player Battletoads game, it's impossible for the second player to even move in stage 11 (Clinger-Winger), and thus he has to lose all his lives for the game to progress? (He can rejoin in the next stage if he has a continue left, for the record.) This proves that Battletoads is SO HARD, especially with two players, that they never bothered completing the game once in co-op just to see if it was playable. And they probably said, meh, if we can't do it, no one ever will. Don't get me wrong, I'm not giving them an excuse, they should've tested that, but still, it's Battletoads. If any game can get even the most dedicated playtester to ragequit, that would be it.