.htaccess Cache lifetime

Ok, so I have my .htaccess set for "ExpiresActive On"and everything is working fine BUT the following will not have an "A2678400" attached to it.

Is there anything I can force to set the freshness on them?

http://java2.techandgamingnews.com/.../heading-bg-2.gif (expiration not specified)
http://java2.techandgamingnews.com/.../redvsblue_wide11-81824_60x60.jpg (expiration not specified)
http://techandgamingnews.com/.../bg.png (expiration not specified)
http://techandgamingnews.com/.../sprite.png (expiration not specified)
http://www.pti.edu/.../buzz_feedburner_logo.jpg (expiration not specified)