Strange 404’s

I’ve added some code to my 404 page that sends me an email every time I get a 404 error. Its been a great way to identify problems in my site and identify bad external links.

There are some strange errors coming up that could be down to web crawlers, bots, or bad code. Does anyone know why these are appearing, and whether I should bother doing anything about them?
eg. http://www.reformstudios.com/tag/oriental-garden/function.require
http://www.reformstudios.com/product_visualisation/whiskey-bottle-render/function.require-once

any ideas