The uber-cool Official Unofficial Freddie Prinze Jr. site had this nifty story, extracted from a log of a recent chat with the Wing Commander actor... (and no, I don't know what's with the 'THIS' thing either).
What is your most embarassing, on-set, moment?
The most embarrassing I ever had was on Wing Commander. I'm getting grilled by the captain of the ship in this scene ... and they wanted me to do a tight salute. So, I make a quick rightface and walk out. They made the ceilings low to have a submarinish feel. And, I turned quick was standing in a different spot, and did a rightface, slammed my head in the corner of this pipe, literally knocked myself out of course. I was flat on the ground! They kept the camera running of course ... it was totally embarrassing!