As a general rule, flashbacks on 30 Rock are nearly always hilarious. Case in point: the biggest laugh to be found in "Retreat to Move Forward" was the flashback to Liz and Jenna's improv comedy days when the audience would shout out Sling Blade and Oprah as suggestions for characters for the two. Liz gamely launched into a Sling Blade impression, but poor clueless Jenna thought she did Oprah.
It's been funny to see Jack and Liz switch personas, or the manatee become the mento, if you will. Jack takes Liz as his crutch to a corporate retreat because he's afraid his business cronies will look down on him after his series of unfortunate events (which includes that stint in the Bush administration). There, Liz is confident and domineering, not unlike Jack in his glory days. Jack, however, is shaken and resorts to given himself pep talks in the mirror to psych himself up for his speeches and public interaction. (Incidentally, another big laugh was the flashback to Liz's similar but much more vulgar mirror self-pep talks.)