Continuity mistake: When Norman is running through the spaceship, he runs through a doorway and you get a glimpse of his facemask. It's dry. After going through water to get to the spaceship, wouldn't there be water on it? (00:43:10)
Suggested correction: On the first visit to the spacecraft, we're told there's heat coming from it. There's no water on the masks of the team during that visit either. If there's enough heat for them to feel it at that depth, it's easily plausible that there's enough heat to dry their masks.
Plot hole: The first time they communicate with the "entity" in the spaceship, they find a correspondence between numbers sent by the entity and letters of the alphabet. The entity presents itself as "Jerry". Later on, the entity tells Dustin Hoffman, "Stop calling me Jerry" - and then Dustin Hoffman realizes that the number-letter correspondence was wrong, and the actual name of the entity was "Harry". But if that is true, how could they have communicated without problems before? The very first word that the entity used was "hello", which would have to be displayed wrong, since it begins with an "h" and has an "e".
Visible crew/equipment: Beth attempts to convince Norman to inject himself with a tranquilizer by trapping him in a room and filling it with water. As the water rises, Norman frantically looks for a way out. There is a quick overhead shot of this scene that flashes on for just a second, and if you look around the perimeter of the room - you will see the entire crew, complete with camera and lights.
Suggested correction: This is simply not true. I have just watched that scene and didn't notice it, so I slowed it down to a third speed and still didn't see it.
Revealing mistake: As Ted is being burnt by the fire, you can see his body trapped underneath the debris. In a side shot of Ted it is very obviously a stunt dummy as the left arm and head stay completely still and the arm remains completely stiff despite hearing screams and shouts from the pain.
Visible crew/equipment: When Norman gets back into the ship, Beth lies down with him for a few seconds. When the camera takes a shot from directly above the two, you can see a crewman's leg in the left side of the screen.
Visible crew/equipment: In the scene after the storm warning has been received, as Captain Harold C. Barnes takes something out of the shelf, a microphone is visible for some seconds at the top (seen on VCR version).
Continuity mistake: When Norman and Harry are talking in the dorm after they hear of the storm coming, Harry is lying down in the bunk telling Norman how they are going to die. There is a shot of Harry's leg at the end of the bunk, then Harry sits up against the wall and in the next shot his leg is still at the end of the bunk, but wouldn't it have moved back when he sat up against the wall?
Continuity mistake: When Norman should give himself the injection, the syringe moves around on the table. First it's parallel to the edge of the table, then at an angle. Later, in the overhead shot, it's lying in a completely different spot.
Revealing mistake: When there's a fire, Beth is waving her fire extinguishers around, but there's nothing coming out.
Continuity mistake: After Harry wakes up after he went into the sphere, he is very hungry, but as he eats, one second he has bacon in his hand, and the next second, no bacon, same with the scrambled eggs: one second, it's on his fork, and the next second, it's gone.
Other mistake: They're meant to be on rebreathers (they recycle the air around the system, so you 'rebreathe' it), yet in the u/w scenes, it can be seen that they're on open circuit systems, i.e. conventional scuba, as they're venting exhaust gases. Rebreathers do not release bubbles in the quantities shown.
Continuity mistake: When the survivors are surfacing in the minisub near the end, the sub is overtaken by a shockwave and lots of huge bubbles. A few seconds later the sub surfaces in perfectly calm, clear water.
