I was thinking that maybe it would be fun to do a review as a community. In other words: how many problems can we spot in a certain text

Interesting idea. Another one would be instead of a certain text we review a piece of code. After all, how often does the average Perl hacker carefully examine the modules they're using? Many eyes make all bugs shallow, but I do wonder how many people are actually reading the source of commonly used modules and trying to find ways to improve them.