Visible crew/equipment: During a close up of the police officer's sunglasses, when Chekhov is asking for directions to Alameda, some crew are visible in the left lens. They are a line of people trying to stay out of the camera. (00:43:30)
Other mistake: When we first see the Klingon bird of prey on Vulcan (just before we see closeups of the "Bounty" written on the side) it is clear that the ship is far too small to contain a pair of adult humpback whales plus 18000 cubic feet of water in its hold. Later, when the ship is hovering above the sea after foiling the whaling ship's attack it seems considerably larger.
Continuity mistake: In the scene where Spock gets confronted after swimming with the whales: you can easily see before he puts on a robe, that his clothes are completely dry, yet he had just been swimming in the shot a moment earlier.
Visible crew/equipment: At approximately 01:32:50 on the Blu-Ray, you can see a diver releasing the mechanical whales. He is on the far right side of the screen, you can make out his head, body and left hand. He is visible for a good 8-9 seconds. If you have a different media source, it's during the Bird of Prey decent. You see a closeup of Kirk, followed by a closeup of Uhura and Gillian, then a close up looking down on the harpoon. It's in the following scene. (01:32:50)
Continuity mistake: The crew wrote 'HMS Bounty' in large red letters on the side of the Klingon Bird of Prey, but in all subsequent flying shots, the large red writing is never seen again. It's not burned off as you only get heat entering the atmosphere if the speed is sufficient, and it's not wind resistance either, because the lettering is missing just after they take off.
Continuity mistake: In the scene with Kirk and Spock walking the marina green under the Golden Gate Bridge, the leading shot shows blue sky. As the camera changes angles, the background changes to completely fogged in. Not shot on the same day.
Factual error: When the Bounty is preparing to slingshot around the sun, the sun is burning a light yellow. From space, it would be white; it only appears yellow when viewed from Earth because of how the visible color spectrum is filtered through the atmosphere.
Audio problem: When Gilliam slams on the brakes, the tires make a screeching sound, but the wheels come rolling to a stop, ergo do not skid. (00:56:50)
Plot hole: If the Bird-of-Prey went to warp speed right after the whales were beamed up the ship would have already been so far away from Earth it would have been on its way back towards the sun, yet minutes later the ship is shown leaving the Earth, still at warp speed.
Factual error: The nuke ETs are sitting at a RADAR station, not a power output monitoring station. The RADAR wouldn't give any sort of indication of sudden additional power draw on the reactor. (01:12:00)
Revealing mistake: When the ship crash lands in the water, and they open the hatch you will see a wall, looks like some piping. When they show the outside of the ship no such wall exists.
Continuity mistake: When we first see the whale pen it is divided from the sea by a concert wall with double gate in the middle, but when the whales are released most of the wall and gates are missing.
Revealing mistake: When Kirk and crew flee the hospital McCoy bumps a man with his leg in a plaster cast. Look closely at the cast - it is fitted over his PJ's leg like a boot, plaster casts are never fitted over clothing.
Factual error: As they descend into the park, Uhura gives a bearing and range of 283 degrees, 15.2 kilometers to the whales, which are supposedly in a marine park in Sausalito. 283 degrees would put you in the Pacific Ocean, because Sausalito bears around 360 degrees from the park. Uhura gives a true bearing to the whales, since a relative bearing would be useless once the crew leaves the park.
Answer: The United Federation of Planets uses the credit. Its a purely electronic form of money. Necessities and luxuries both are simple and cheap to produce with the Federation's advanced technology, and humanity has matured to the point that accumulating wealth is considered vulgar. Furthering the common good or the advancement of humanity is the real status symbol in the 23rd and 24th century. These conditions result in a society with very little need for money. Citizens are paid, but since the technology built into a place of business (or starship) or home supplies all basic needs for free, most people spend money only on exotic products that aren't commonly manufactured, like art or handmade foods.
Grumpy Scot