Visible crew/equipment: Watch the special edition version of the movie. During the scene when the crane is falling down on top of the sub, the camera is following people around the passages. When it comes to the end of a hall, and a hatch is shut in our face, we can see the shadow of the camera equipment in the door.
Factual error: When Lindsay is being revived after Bud towed her back to Deepcore, I understand why the CPR being done isn't exactly correct(due to the fact the actress isn't really dead) but the filmmaker neglected to notice that when the crew proceeds to shock Lindsay, she is wet and on a metal floor. Not only would she be shocked, the entire crew around her would be shocked as well.
Continuity mistake: When Lindsay is pulled from the pool after she drowns her wet hair is covering her face. In the next shot she is laying on the floor and Bud is smoothing her hair back to give her CPR. The shot changes again and her hair is back covering her face like it was when they pulled her from the water.
Add timeTina Gilliam
Continuity mistake: When Bud leaves Jammer behind in the sub, he gives him a strand of rope to keep the two connected. At first Bud keeps the bundle of rope and hands Jammer the loose end, however in later scenes it's shown that Jammer holds the bundle of rope and Bud holds the loose end; as Jammer is feeding him line.
Visible crew/equipment: During the scene where Bud and Lindsey are arguing about who will wear the scuba equipment back to the rig from their downed mini sub, a hand with a cloth wipes water off the camera. It's during the line when the camera is facing Bud and he says "Don't argue with me goddammit, just put it on." This is visible in the 4:3 version for TV, as well as the widescreen version on DVD.
Plot hole: Granted, Coffee is suffering from "high-pressure nervous syndrome," but if you're a Navy SEAL, wouldn't you notice whether or not your pistol has a magazine in it? Monk pulls the clip out of his jacket and starts knocking rounds out of it for the rig crew's benefit; the same dramatic effect could have been achieved with a handful of cartridges he could let slip through his fingers. You could argue that Monk didn't have enough time to unload the gun and replace the magazine, but in that case, I think the scene where Monk briefly had the gun should have been a bit longer. (Even had the empty magazine been IN the gun, Coffee still might notice the difference in weight, but that would be easier to suspend your disbelief for.)
Continuity mistake: When Bud and Lindsay are in the sub after the big chase, water leaks in and Bud searches for something to fix it. He delivers some dialogue while opening (I believe) a first aid kit. The camera angle switches to Lindsay as she says something, and Bud can be seen in the background opening the kit once again.
Revealing mistake: After the water tentacle sequence, Coffee brings Schoenick back to their bunks to get the submachine gun, so they can take over the rig. The bag containing the gun is stashed behind some pipes up by the ceiling. Watch when he reaches behind the pipes to grab the bag--the pipes move at least six inches.