There are a few basic jobs you need to get right when you're a stagehand working on a movie. Make sure you get the lighting rigs in the right place. Make sure the sound equipment is set up and working properly. Make sure the area you're filming in is locked off from the public. And do not, in any circumstances, walk across the set when filming is going on. Here's a guy who couldn't handle the basics.
In the very first movie in the franchise, when Jack Sparrow shouts out "On deck, you scabrous dogs!", Johnny Depp must have been really convincing in his performance. So much so that this guy jumped on deck right behind him, wearing his aviator sunglasses and his stetson. Either his sense of style was even more unique than Sparrow's, or he's blundered into a scene he had no business being in, and nobody noticed.