When we first see the hard candy jar sitting on the shelf, each piece of candy is wrapped in cellophane. When the jar is opened, each piece is unwrapped.
At the beginning, when the Death Ship is steaming full ahead at the cruiser, it is twilight. However, in the shots of the cruise ship it is clearly nighttime.
After the cruise ship goes down and they show the lifeboat for the first time, the captain is sitting in it on the left, even though the other survivors don't pull him from the water until a few minutes later.
It is implied after screens in the boiler room in which the ship's engines can be seen running that the ship has gotten underway on its own after the cast boarded it and this is backed up several times both before and after by shots of the bow at the waterline with heavy foam implying motion but it had long since been made clear by a mooring line clearly exposed heading over the bow from the second deck that the ship was stationary.
In the 86th minute, a voice from the ghost ship says 'posizione.' This is not German.
Early on, in the escape boat, survivors find something white floating several inches or feet below the ocean surface. They pull 'it' up, and it's the ship captain. He would have been dead after floating hours below the surface.
Early on, when the survivors move from the escape boat to the derelict ship, all move to the ship except for the injured captain and one other crew member, who calls back another crew member to the boat to assist with the extrication of the captain. Very unrealistic.
While two other characters are carrying the captain (George Kennedy) up the steps onto the derelict ship and they fall into the water, the captain is an obvious body double because he's wearing a thick gray wig and Kennedy is balding.
When Marshall drops the anchor to stop the ship so that they can make their escape, the overhead shot of the anchor falling into the water clearly shows that the ship is not moving.
When Treavor and several passengers are exploring the ship early on, Trevor opens a sailor's unit where, over the bunk, there is loosened cotton batting. Presumably, this is meant to be spider webs.
When Ashland enters the bridge for the last time the captains chair has disappeared, but is shown again once the ships takes control of itself to ram the other ship.
When the wire that lifts Jackie up the air is shown on the deck it is run through a loop with no sort of release mechanism present. However, after a few frames of him in the air you see that it now has some short of release mechanism for dropping him. Also, when the noose first tightens it is around his ankle, but after he is dipped you can see that the line is actually run down to his waist (really noticeable as he is rotating).
When Nick is trying to free Lori from the shower by smashing the glass door, you can clearly tell that he is hitting the metal part of the door with the board and not the glass.
When Marshall is searching the meat locker where the bodies are hanging, despite all the bodies being covered in ice indicating that it is extremely cold inside, Marshall's breathe never shows as it ordinarily would.
Towards the end when Marshall jumps out of the hatch to tackle Ashland he is jumping towards the outer railing, but when the camera angle changes is movements are in the opposite direction. Even assuming the he over jumped and passed Ashland, the hatch that he jumped out of would be visible behind him, but it is not. The struggle was obviously shot at a different point along the ship than where the hatch was located.
At the 51-minute mark, there is a sequence in which the character played by George Kennedy emerges in a dark uniform atop the ship while the character played by Richard Crenna looks from below. During three separate long shots of Kennedy, a crew member and camera are plainly visible on the left side of the shot.
When the group first comes up upon the ship after it sunk the cruise ship, you see one of the windows open up, you can clearly see a person's arm when he opens the window, it is supposed to be opened by a ghost, which it clearly isn't.
Cameraman's shadow visible in the beginning.
At the beginning, just after the collision, the surviving characters are seen drifting on the ocean on a wooden platform. George Kennedy's character is plainly visible lying down with the group, even though he hasn't yet been pulled out of the water! He appears from below the water about two minutes later.