Revealing mistake: When Charlie is climbing the wall you can see a handhold screwed into the wall when she lets go with her right hand. (00:59:45)
Continuity mistake: When Tyler is resuscitating Katherine he cuts and then rips her swim suit down to her belly button, but in the next shot when she is climbing up the cliff the cut is only up to her breast bone and has a zip on it.
Continuity mistake: When Briggs is talking to the rest of the team on the fiber optic line, the counter on the video screen jumps backwards between shots.
Factual error: The dive crew says they are using rebreathers as dive gear. Rebreathers do not produce bubbles, but most of the underwater shots show the team making bubbles.
Plot hole: Tyler jumps into the water, then grabs his mask and puts it on and begins swimming, but he fails to clear his mask by blowing the water out of it. Without clearing it, he wouldn't have been able to see a thing.
Other mistake: About halfway through, the divers go into water with a very strong current, and yet both Catherine and Nicoli both call Tyler to come to them, which is impossible - the current is too strong for Tyler to even attempt to turn around and go back to them. Both Catherine and Nicoli are in the current, so they will come to Tyler, eventually, when the current isn't so strong and Tyler can hang onto something and wait for them.