It just doesn't retain knowledge long term or maintain logical consistency for very long.

If your next prompt after this story was something like "Batman starts clearing the rubble from explosion, looking for survivors." it's just as likely to make up some entirely new reason for there being rubble or say that Batman himself detonated the bomb as it is to "remember" that there was a bomb that went off and it was detonated by the Joker. And 6 or 7 prompts from now? No way.