Yes it can be bad for your site and 500 of em' surely isn't good. If you have wordpress you can use a redirect plugin. Theres a few and it's been a while since I've used one, but I beleive it was the "Redirect All 404 To Homepage" or something like that.
Thats an easy way.
If its the plugin I used a few times in the pas, it allowed me to redirect whatever page I wanted and redirect it wherever I wanted it to. This is really what you want to do with pages that have any SEO value, because you can redirect to relevant pages and not send everything to the homepage. Which is the right way.
Or you can redirect in the htaccess file with:
Code:
redirect 301 /old/oldURL.com http://www.newURL.com