Revealing mistake: During the fight scene in the belly dancer's room, Bond spins the bald guy around to avoid being hit by a chair. When the bald guy gets hit in the back with the chair, you can see a large rectangle of padding under his jacket.
Continuity mistake: During the chase scene with the police, Bond swerves past a driver in a dark green 1956 Plymouth Savoy. As the police cars pass the Plymouth, the scene cuts to an inside shot of the car with the driver yelling, then the driver loses control of the car and rolls it over. The car that crashes is a green 1955 Chevrolet 210 series, not the 1956 Plymouth.
Visible crew/equipment: When Bond tries to get the golden bullet from the belly dancer named Saheeda, some angry gangsters enter her dressing room. As they start destroying the place, you can see the crew in the mirror on the dressing table very clearly after one of the bad guys is knocked into it, nudging it out of position. (00:17:35)
Plot hole: When Bond and Scaramanga are dueling, Bond has no tie or jacket on. After Bond drops his gun and gives his hiding place away, he somehow has the time to not only crawl back onto the staging, but to move the wax replica of himself, and also to put on the dummy's jacket and necktie.
Continuity mistake: When Bond is flying over China and landing on the sea by the Scaramanga's island you can see that his plane has two floats - one on either wing. But in the shot where he is heading for the beach it is clearly seen that the left float has gone! (01:28:40 - 01:30:55)
Revealing mistake: At the start of the film when the gangster lands on Scaramanga's island, and enters Scaramanga's fun house, he encounters a scene where some dummies of Al Capone and some other gangsters come out of an area guns blazing... With the first burst of machine gun fire, the dummy "blinks"... (00:05:25)
Factual error: The film's car chase takes place in Thailand, where vehicles are right-hand-drive (RHD) and travel on the left side of the road (as in England and Australia). Yet the American Motors (AMC) cars in the chase (the red Hornet X, gold Matador coupe and several Matador sedan police cars, all 1974-models) are all left-hand-drive cars. Scaramanga's car can be excused as something he specifically imported for himself, but the Hornet is 'borrowed' from a fictitious AMC dealership (none existed outside the USA) and the small amount of AMC vehicles sold outside the USA were shipped disassembled to various companies that reassembled them and sold them under their own company names (AMI in Australia, Karmann in Germany, etc). Companies such as these, in RHD nations, had to modify the cars to RHD themselves in order to be allowed to sell them 'locally'. So the Hornet would have been at a non-AMC dealership, and would have been RHD, as would the fleet of police cars. Naturally, this 'error' was created by AMC's promotional deal with the filmmakers to use AMC cars in order to improve US sales to the US filmgoers.
Revealing mistake: In the shot where Bond rams the long tail boat of the karate experts, you can see that the boat is split in two pieces and the bow is already sinking before the collision. (00:59:30)
Factual error: The liner Queen Elizabeth sank in the Hong Kong harbor in 1972, not 1971. (00:24:55)
Visible crew/equipment: James Bond is backing up the red AMC Hornet X, preparing to jump the wooden bridge. Sheriff J.W. Pepper says, "What the hell you doing now, boy?" and then you can see a studio light and a crewmember in the reflection of the right rear passenger window. (01:26:25)
Visible crew/equipment: During the car chase scene where Bond is driving the red AMC Hornet X, Sheriff J.W. Pepper says, "The nearest bridge is two miles back." Look at the rear window and you'll see the elbow of a crewmember on the roof of the car appear into view. (01:26:15)
Continuity mistake: The AMC Matador stops as the AMC Hornet X races by on the cross-street. As the Matador halts, we see it has a proper door mirror. In a close-up of Scaramanga driving, we can just see the hole in the door where the now-missing mirror was mounted (on the VHS full-frame, we can see the remote cable hanging from the hole and the base of the mirror swinging as the mirror hangs out of view). (01:24:20)
Continuity mistake: When Nick-nack realizes that he and Scaramanga are being followed, there is no round, white decal at the lower corner of the windshield of their AMC Matador, yet in all other shots, the decal is there. (01:22:20)
Continuity mistake: When we first meet Francisco Scaramanga we see that he has a third nipple which is just above his left. The next time we see him he is lying on a beach chair showing the left of him. If you look carefully you will notice that there is no third nipple. (00:06:33)
Visible crew/equipment: In the scene where Bond walks in on Scaramanga's girl in the shower, you can easily see a crewman in a mirror as the camera pans. (00:28:20)
Continuity mistake: When the AMC Matador arrives in the hangar and begins attaching the jet plane equipment, we see a bracket welded to the lower rear quarter panel, just behind the door. The wing supports swing down to attach at this point on both sides of the car, yet these brackets were not on the car in any prior shot. (01:27:35)
Continuity mistake: A significantly modified '74 AMC Hornet was used for the famous cork-screw jump sequence, taking the place of the relatively stock Hornet X used in all other shots. It is best viewed just after the jump as the car slows to turn left - the car has a much lower stance and the wheel wells are far larger. (01:26:50)
Revealing mistake: When Nick-Nack pulls the money from the dead gentleman who Scaramanga kills in the game before opening credits, you can see a "wax figure" of James Bond pointing his gun. But he is moving, and not standing completely still like a wax character/mannequin would. (00:07:55)
Factual error: James Bond comes out of the "Bottoms Up" topless bar and down to the waterfront. He jumps on a boat and tells the boatman to take him to "Kowloon side". In fact, Bottoms Up is on the Kowloon side of Hong Kong harbour, so he's already there. If he wanted to cross the harbour, he should have asked for "Hong Kong side". (00:35:25)
Revealing mistake: Scaramanga's jet-car fires up its roof-mounted jet engine and begins to roll forward in the hangar. Despite the fact that we hear the turbine whining loudly at increasing RPMs, the flimsy tan sheeting hanging in front of the jet intake is not sucked in, or even disturbed at all by the air flow. (01:29:05)
Answer: I haven't been able to find any information on its whereabouts so my guess would be that ended up like most movie props do. Either as a souvenir for one of the people attached to the movie, (actor, director, etc.) in storage (in case it could be recycled as a prop in another movie) or simply discarded when it wasn't needed anymore.