Squee! It’s just Firefly memories all over the tube tonight, as Summer Glau pops up playing herself on The Big Bang Theory. In addition to her time on the Serenity, you may remember Summer Glau from her recent regular gig on Terminator: The Sarah Connor Chronicles, with her genes modified on The 4400, and in a recurring role on The Unit. Tonight’s outing finds her trapped…er, traveling on the same train as Sheldon and Leonard, who are starstruck by her greatness. We might be the same. Tonight on CBS at 8 Eastern and Pacific.