URL rewrite hacking attempt?

Question

I have a re-write URL on an Nginx server in the form of the following:

/title-xx/ /getTitle.php?title=xx

And the method used is:

$titles->getTitleDetails( xx );

Now what I've recently spotted from access logs is somehow someone has managed to find out the method name and has been plugging it into the URL request:

/title-'.%20$titles-%3EgetTitleDetails()%20.'/nameofmovie.html

I'm guessing the site might have been edited live at some point and an error message exposed what the function name was but, what I'm puzzled about is what do they have to gain by making it part of the URL request.

Is there a certain type of attack I should watch out for?