As most of the divers were amongst the world's foremost u/w filmmakers, and they regularly deal with carting around hundreds of pounds of equipment underwater, I'm kind of thinking that it's not they who are likely to need refresher courses...
Actually, as I understand it, the hit was pretty serious. They did kind of dramatize it in the movie, but then they immediately moved on in the movie... not so much in real life. (Yes, of course they moved on in real life and Howard is OK now, but it was pretty serious.)
Don't recall this, but if you're sure that it's there, I would say something to them. They're very conservation-minded and I'm sure that they wouldn't want their message diluted in that way. If it's there, a gentle reminder of what that does to their message might be well received.
It's Howard & Michele Hall
http://www.howardhall.com/