Somewhere, some ops engineer is being pinged because the alerting system has noticed a huge increase in hits to the error page.
Access logs often include the HTTP Referer header, which would make it easy to see that all the traffic is coming from Hacker News.
Even so, if I were the one to submit the URL to Hacker News, I'd probably make the URL path something like /showing_404_page_to_Hacker_News so it's impossible for someone reading the access logs to wonder what's going on.
The engineer then sat back and smiled at how their server continues to serve this page just fine despite the HN demand :)