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)
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 Spock is dying within the glass confines of the ships nuclear power source room with Admiral Kirk (William Shatner) on the opposite side of the glass, in one scene speaking to Spock, Admiral Kirk's red Federation uniform jacket lapel is unbuttoned at the top. In the very next scene the uniform jacket is buttoned. (01:40:10)
Continuity mistake: Spock's funeral takes place in Torpedo Bay 1, on the starboard side of the ship. The interior shots, however, show Torpedo Bay 2 (you can see the label and the airlock from the beginning of the movie). In addition, the arm that lowers the torpedo is marked with a '2'. Making matters worse, Torpedo Bay 2 was destroyed in the battle with USS Reliant. (01:43:20 - 01:44:45)
Continuity mistake: The blood stain on Kirk's jacket keeps moving around.
Revealing mistake: When the Enterprise is leaving space dock, look at the right (starboard) side of the ship. You can see the shape of the mounting arm the model was mounted on, even though it was blacked out to look like space, and it also blocked out the bottom of the dock. The footage was reused from Star Trek: The Motion Picture.
Audio problem: When Kirk makes his "old wounds" remark to McCoy, just before he steps out of the turbolift, we can hear the sound used to indicate the turbolift is moving, but the door is already open.
Continuity mistake: When Kirk and McCoy are in the turbolift, just before Kirk is told about the message from Carol Marcus, they are both standing right next to the door, but in the close up of McCoy, right after Kirk is informed of the message, McCoy has suddenly moved along the wall.
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.
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.
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: 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: 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.
Chosen answer: According to the novelisation of the film the Genesis project was initially designed to be capable of creating an entire solar system. While the focus of the project eventually narrowed down to altering an individual planet, the sub-routines necessary to create a star were still in place and were activated when the device detonated within the nebula.
Tailkinker ★