I have a craft installation and recently my server had issues and on the page rendering mysql and other errors were shown.
Of course this creates security implications. Is there a way to restrict these errors? My guess it that i just need to change the devMode to false in general.php. Is there anything else i need to do? I am asking because I cannot really reproduce the error anymore.
Your guess is correct... as the docs say, you should never have devMode enabled in production environments specifically for reasons like this (as well as many others).
If you find errors that are leaking sensitive server info with devMode disabled, then that is a bug and should be reported to support@buildwithcraft.com.
