It's from episode 30 (or is it 29?  I need to 
watch my tapes ;_;) when Kenshin is fighting 
Saitou.   During the fight Kenshin reverted to 
being the Hitokiri Battousai... thus the yellow 
eyes.  He's fighting so hard that his hair tie 
conveniently falls out  ^_^

Best Wishes,
Jenny