Extension plugs

I have an extension plug here (you know, one that lets you stick a couple of devices into one electrical outlet. It looks roughly like this:

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Two prongs, since most plugs round here don't have earth connections. Now, carefully, one prong is longer than the other, in order to avoid getting the thing in the wrong around. But, can you spot anything wrong with the way that this plug is designed? Think about obvious failure modes.

Yes, it's possible to plug something in the wrong way round using two adjacent slots. I have no idea what effect this has, but I've got rather attached to having uninterrupted power, and I'd like to keep it that way, so I'm not experimenting.

In other news: although you may have been advised to boil your water before consuming it, you are allowed to let it cool down from boiling before decanting it into a plastic bottle to put into the fridge so that you can enjoy cool water later that day. That is all.