Continuity mistake: When Engineering is taking damage and the trainees are fleeing, Scotty's nephew goes to the aid of an injured crew member. A containment bulkhead is lowering to seal the compartment as he approaches it and as the shot ends, the bottom of the door has reached the lowest edge of the round collar at the left of the screen. Moments later, the actual rescue is shown while the door is lowering through the same area as before- having started higher than it was when the prior shot ended. The change in camera angle is not creating an optical illusion. (Director's Cut DVD). (00:50:35)
Continuity mistake: In the Kobayashi Maru, Dr.McCoy is knocked to the deck unconscious, his head on a support; next shot shows McCoy's head lying on Sulu's leg; next shot shows McCoy's head back on the bare deck.
Continuity mistake: In the training simulator at the beginning of the film, after Sulu and McCoy have both fallen, McCoy has his head resting on Sulu's hip at first. Then, in the next shot, his head is resting closer to Sulu's knee. (00:05:50)
Continuity mistake: The Enterprise is (slowly) attempting to put distance between herself and Reliant (which is about to explode). Whenever Enterprise is shown coming toward camera (or watching Reliant on its viewscreen), Reliant is alternately seen from its starboard side pointing at our 2 o'clock position, from port/aft listing hard to starboard, from it's aft/top area, pointing toward 1 o'clock, and from starboard/bow pointing to 5 o'clock... yet Reliant isn't wobbling or moving, and Enterprise maintains a straight (shortest) course away from her... all suggesting Enterprise is traveling in four directions at the same time. (Director's cut DVD). (01:36:50)
Revealing mistake: Near the end when Khan says "For hate's sake, I spit my last breath at thee", if you look near the bridge of his nose you can see the prosthetic of his "wounds" is coming loose.
Revealing mistake: When Chekhov and Terrell see the Ceti Eels moving around in the tank for the first time, it's obvious that it's not sand in the tank. As the creatures move underneath, all the 'grains' move in unison, and not a single grain of sand is disturbed nor do they tumble over one another.
Continuity mistake: In the Genesis cave, Kirk puts on his glasses to look at his watch. In the very next shot, he is not wearing his glasses. (01:15:20)
Audio problem: On Ceti Alpha V after Chekov urges Captain Terell, "We need to get out of here," we hear Terrell respond with "But the tricorder..." But his lips actually say "But the child..." The line referred to a deleted scene so it was recorded over in post.
Revealing mistake: On the Regula station, when Kirk, Saavik and McCoy set phasers to stun, McCoy is squeezing the trigger on his as the emitter light is lit. He is still holding it down as he turns to walk off.
Continuity mistake: When Kirk is marooned by Khan, Carol asks David to show them the Genesis Cave and he says "we can't just sit here", Kirk puts on his glasses, looks at his watch and replies "yes we can", in the very next shot the glasses are gone as David stands up.
Other mistake: As the turbo lift doors open for Joachim to say his line, the diagram of the lift system on the back wall is of the Enterprise's system.
Other mistake: On the Reliant, as the woman turns and goes to activate the transporter, the blue diagram on the monitor above and to the right of her head is the port and top diagnostic views of the Enterprise, rather than the Reliant.
Continuity mistake: When the Enterprise leaves spacedock, Saavik orders 'one quarter impulse power'. However, in the exterior shots the impulse engines are not lit. The reason is that ST II uses stock footage from ST I for the spacedock scene. In that movie, the ship leaves the dock using thrusters. The obvious give away is the blue deflector from ST II forward, while ST I had a red deflector. It is a short scene less than 2 seconds, you really have to watch for it. The thrusters are on, as seen in the parts of the scene with the blue deflector, and suddenly they are off and the deflector is red for a few seconds.
Continuity mistake: In the scene when Khan first opens fire on the Enterprise, the exterior shots show the damage on the forward part of the engineering hull. However, the damage on the interior shots is occurring on the aft section. Which is to say if the exterior and interior damage lined up the way they're supposed to, Scotty and his cadet engineers would've all been killed in a warp core breach. (00:50:15)
Plot hole: Khan said that the crew of the Botany Bay had been stranded on Ceti Alpha VI for 15 years. Considering that most of his crew were in their 20s, wouldn't that mean they were all children when they were first stranded? In the original TV series, all of these superhumans were already adults, so how come Khan was the only person to age? (00:19:40)
Revealing mistake: When Chekov and Terrell are walking on Ceti Alpha V watch as they get to the ridge overlooking the Botany Bay. Each of them cast two very distinct shadows, indicating two separate light sources. The planet only has one sun. (00:15:05)
Continuity mistake: When Khan contacts the Enterprise after Reliant's opening attack, Kirk has his uniform jacket unbuttoned to about mid-chest level (a little above his stomach). When Khan demands all information on Project Genesis be turned over, and Kirk responds with 'Genesis? What's that?' his jacket is now unbuttoned all the way down to his belt.
Revealing mistake: After crippling the Enterprise, the Reliant comes around again. As it does, the star field behind it can be seen through the black area of the inside of the nacelle.
Continuity mistake: After the reliant explodes and the Enterprise is safe, Kirk goes to engineering to see Spock in the radiation filled chamber. During this entire scene, Kirk's tunic is open as Scotty and McCoy keep him from entering the chamber. As Kirk approaches the chamber to talk to Spock, the tunic is partially closed. The next shot shows the tunic all the way open as Spock walks towards Kirk. (01:39:55)
Continuity mistake: When Captain Terrell kneels down and says "What the hell is that?" Chekhov's gloved hand can be seen on the left side, but in the next shot Chekhov is already in the next room.
Answer: Lt. Marla McGivers was the crew member.