Factual error: When Bond is flying from Europe to Baltimore on his way to Goldfinger's studfarm in Kentucky, Pussy states that they are flying at 35,000 feet. Flying west, they would fly at an even altitude, not odd.
Factual error: Goldfinger says his Rolls is made from gold, but the magnetic homing device clings to it. You can't attach a magnet to gold.
Plot hole: Goldfinger wasn't planning on Mr. Solo breaking away from the rest of the gangsters before Goldfinger could have them all killed by the nerve gas so it makes no sense that there would already be a truck from the stud farm waiting for Oddjob to drive back with the remains of the crushed car. It also begs the question if Oddjob had to drive the truck back to the farm where is the guy that drove it to the junkyard in the first place?
Revealing mistake: The rear projection behind Bond as he is driving through Geneva doesn't match the scenery outside his car.
Continuity mistake: Near the start when Bond and Moneypenny are talking about gold, she throws his hat at the hatstand. The top of the hat is facing left as it flies offscreen, but when the shot cuts to it landing it's turned itself around so it can catch properly on the hook. Plus it lands on the hook furthest from the door, but when Bond leaves he picks it up from a closer hook.
Continuity mistake: When Bond comes around on the plane and meets Pussy for the first time, she tells him they are flying SW over Newfoundland. The clock on the restroom door shows 10.05am. Later, when she announces arrival in Baltimore in 55 mins, the clock is now showing 2 .45pm giving arrival time of 3.40pm. Flying time would have been approx 3 hours, arriving at 1.05 pm.
Revealing mistake: Before Goldfinger is sucked out of the plane, the flying cushions (superimposed on a chroma) magically vanish.
Revealing mistake: When Oddjob is killed and falls face-down, he turns his head to the left a second before he smashes it against the floor.
Continuity mistake: When Oddjob arrives at the junkyard, it's a cloudy day and the car casts no shadow; however, a shot later, from a different angle, it's a sunny day and there's an 8 o'clock shadow beneath the car.
Continuity mistake: After Bond hits Oddjob with the stick, Oddjob launches him face-down, but from the next angle Bond is landing and sliding face-up.
Revealing mistake: When Bond grabs a huge stick to attack Oddjob, the first wide shot behind Bond is of a very obvious stuntman with a square face and a prominent jaw. Stunt also visible after Bond jumps and grabs Oddjob's neck, when he is launched against the wall.
Revealing mistake: When Oddjob throws his hat at the statue and the head comes off the head falls on top of the arm and breaks it. Obviously this was not meant to happen as there is a quick edit in the film before the arm falls completely off (notice the trees behind the statue suddenly freeze).
Revealing mistake: When the CIA guys are following Odd Job to the airport in "Kentucky" there are several indicators that show they are in Florida. One is a big sign that says Opa Locka, which is north Miami.
Character mistake: Goldfinger is holding a S&W .38 in his plane. Bond says (in his explanation about shooting guns in planes), "That's a Smith and Wesson .45."
Other mistake: At the 17th hole, on his "drive" shot, Goldfinger actually hits a straight drive that never leaves the ground. (00:28:01)
Factual error: When Goldfinger's pilots fly over Fort Knox to deliver the sleeping gas, they could not have done this in real life because Fort Knox is in a no fly zone. Fort Knox's airspace is a 3.5-mile radius and it goes up to 3,500 feet. They'd have been intercepted in no time. (01:29:06)
Other mistake: When Q briefs Bond about the Aston Martin, he tells him the homer (tracker) has a range of 150 miles. When Bond is tracking Goldfinger in Switzerland, he is momentarily distracted while Tilly overtakes him. The blip on the screen has then disappeared, meaning G's car is some 150 miles ahead. But moments later, Bond pulls up on the hillside above where G has stopped for refreshments. How could he have made up the best part of 150 miles in so short a time?
Other mistake: Inside the plane Bond punches Goldfinger's chest. However, Goldfinger reacts as if he had been punched in the face.
Plot hole: As Goldfinger points out there are 41,000 troops stationed at Fort Knox so how in the world was Goldfinger able to make his escape? The troops should have easily been able to overpower Goldfinger's men without much of a fight and certainly shouldn't have been so easy for Goldfinger himself to get away on the helicopter.
Continuity mistake: The wall separating the cockpit of Goldfinger's private plane seems to have disappeared when Mai Ling is waiting for Bond to lower the steps of the plane as she can be seen standing right behind Ms. Galore's seat.
Chosen answer: They're not. Q was just indicating to Bond that these were the wing machine guns, he wasn't stating which was which.