How? the only thing that being a Wal-mart bike would have to do with it is that it's a bike. It might be argued that it might not have happened on a more expensive bike, but that would only be because a more expensive might (but not necessarily) be more likely to have a more experienced rider.

The OP gave enough clues to explain this as a form of rider error, too fast into turn, followed by front wheel braking during the turn. Could the bike itself have been a factor? Of course, but no evidence points directly at that.