Fast forward to where the Cave of Wonders is falling apart. When Abu is jumping on the stones to avoid getting barbecued, some of the stones don't explode.
Why would they need to?! The whole point is that the cave is trying to kill them for disobeying his orders. Why would he need to destroy ALL of the stones when all he has to do is get rid of the ones Abu can reach? Sorry, but this isn't a slip up.
What I always noticed about this scene is that some of the rocks reappear and then explode again. Which might be what the guy who posted this was talking about.