The image that's supposed to show up on the "Page not found" page is missing:

Maybe it's just Chrome, but the image is sitting on a server that's different enough from stackexchange.com, it doesn't like it, when accessing the image that's supposed to be there:
https://sstatic.net/gamedev/img/404.jpg
This is what Chrome says:

Anyway, it's a minor thing, but it might happen with other things that are more important if they're similarly hosted on https://sstatic.net/gamedev/

https://cdn.sstatic.net/gamedev/img/404.jpgand I get no warnings when visiting it. The SSL cert is valid and issued by GlobalSign nv-sa on 30/05/2013. \$\endgroup\$