Watch your head, TK-421

This is probably old news to most of you, but on the off chance that a few of you have not seen this priceless Star Wars blooper, I must post it. During the escape-from-the-Death-Star sequence midway through the film, a group of stormtroopers comes through a door; watch the one on the right closely:

It happens very fast and is easily missed if you aren't paying attention. The sound of his helmet smacking the bulkhead is audible, so I assume it was deliberate. Nevertheless, I watched this movie dozens and dozens of times throughout my childhood years before noticing it one day in college. It was something new in a film whose dialogue I (and most of us back then, before the dark times, before the Empire) could recite entirely from memory. I recall scrambling frantically to the orange dorm room phone to summon my fellow SW geek Jeff, one of only two people I know who can recite poor doomed Greedo's cantina dialogue in the original Rodian. We probably rewound the tape (VHS, in those days) to watch that scene 20 times.