I saw the movie this evening and I have some positive and negative things to say about it.
First and foremost, I am a newer diver with only 30 warm water dives, so I am not speaking from a TON of experience, but here are my observations.
1. The divers had their "open water" certifications and thought they had enough experience to break away from a group in an area that they presumably had not dove before. I view the open water cert as an "entry level" certification into diving. I received mine a few years ago, and I don't think by any stretch of the imagination that I am qualified to go out on my own with a dive buddy who has the same amount of experience in waters that I am not familar with.
2. The divers did not have any emergency equipement with them, I.E. no safety sausage, strobe light, noise making device etc etc etc
3. And this is just a personal observation on my part, it wouldn't really be considered a mistake.....but I try to get to know the people a little bit that I am diving with. That includes the other vacationing divers, the divemaster, and the captain on the boat. The charachters in the movie basically for the most part kept to themselves, and when it was time for the boat to leave, nobody missed them.
4. In the movie, one of the charachters said that divers being left at a dive site is more common than most people think. I couldn't find any evidence to support that online, and the dive operators I have been with have either used a whiteboard, put peoples names up on it, and checked the names off as divers returned, or had a clipboard with signed insurance waivers to double check. I am sure it has happened more than once, but I doubt it happens as often as the film would want it's viewers to believe. I imagine that dive operations are like most other things in life, there are always a few bad apples. Of course, there are also message boards like this that one can go to, to get opions on those operations.
On a good note, the movie didn't make sharks out to be monsters lurking in the waters waiting for human flesh. Also, in the movie they did go over some hand signals, and little safety things like having a snorkel, or your regulator in your mouth until you exit the water.
Overall, it was a cheaply made film, and I think in the long run it probably won't hurt the diving community. It won't keep me out of the water, but before going on that next dive, I will be purchasing a safety sausage/strobe light, and it might convince other divers to do so as well.........