What's the Big Frigin' Difference?!

There are some hidden differences in these tricky pics. Are your eyes sharp enough to spot 'em?!**HINT -- There are THREE differences in the above pictures!**

Source: http://www.tmz.com/2012/02/11/whats-the-big-frigin-difference-celebrity-hunt-pictures/

Kirk Douglas Mike Douglas Patty Duke Faye Dunaway Bob Dylan