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)
Continuity mistake: When Bond is flying over China and landing on the sea by 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)
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)
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)
Continuity mistake: The red AMC Hornet X that Bond steals from the car dealership alternately does, and does not, have an interior rear-view mirror mounted on the windshield.
Continuity mistake: When Scaramanga is talking about the laser gun to Bond, the water is next to his airplane but when he shoots on it, the level is lower. There's only little waves so it's impossible to change that fast. (01:36:55)
Revealing mistake: During the intro, the first Bond "dummy" and the second one when Scaramanga fires are different. They're either real and dummy or both dummies, but the first one has a concentrated look, and the second one has a worried look.
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.
Andreas[DK]