I can only assume that “Knock Off,” the new Jean-Claude Van Damme movie, was a Jackie Chan vehicle with a script that Chan wouldn’t go for. The trailer left no doubt that this was indeed a Chan movie, complete with signature Jackie moves and a Hong Kong angle, but with a much taller, much less endearing Jean-Claude in Jackie’s role. Or maybe they wrote the script and then found out Chan had already signed on to do the questionable buddy flick “Rush Hour”, forcing J-C to do some quick training in ladder-fighting and monkey-like gymnastic moves. If there’s one thing the movie got right, though, it’s definitely the title.