I've noticed that in SO sites some URLs don't give the standard error "Page not Found" with the waffles but a 404 error.
For example these URLs: https://meta.stackexchange.com/a/a/a/a/a/a/a/a/a/a/
are giving the standard error page, but if I add another slash (the 32nd), the Web Server gives another page, in some way "out of control":
I don't know if it's so important to notice but I wanted to try, because I work as programmer and sometimes customers request that any wrong URL of the same kind should give the same error page.
Note: I've tried with google.com and the result is worse even with just /a/a, so maybe the problem is not so important. :)