Revealing mistake: When Nick-Nack pulls the money from the dead gentleman whom Scaramanga kills in the game before the opening credits, you can see a "wax figure" of James Bond pointing his gun. However, he is moving and not standing completely still like a wax character or mannequin would. (00:07:55)
Plot hole: Scaramanga kills his boss Hai Fat in cold blood inside Hai Fat's massive estate in Thailand, but even after Hai Fat's attache runs inside and sees Hai Fat dead, murdered by Scaramanga, the attache and Hai Fat's security personnel in the heavily guarded complex permit Scaramanga to leave without being apprehended for the murder of their boss with Scaramanga glibly stating "Mr Fat has just resigned. I'm the new chairman of the board" as he walks out of the room untouched. (01:04:50 - 01:05:25)
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.
Revealing mistake: At the end of the film where Nik Nak is throwing unopened bottles at Bond from the junk's bar area not one of them appear to have any liquid in them. Bond never got wet and neither did the sheets on the bed or the floor.
Continuity mistake: Bond tells the kid he'll pay him 20,000 bahts if he manages to start the engine, which he does. Shot changes and the kid spreads his arms wide and smiles with joy. Back to the wide shot and his arms are closer together, and he has a worried look. (01:00:30)
Continuity mistake: When the Hong Kong police are chasing Bond, they use three black and white AMC Matador sedans. When they arrive at Scaramanga's hanger, we find that two of the three Matador police cars have been resprayed in red.
Other mistake: Ms. Goodnight was surprised to learn that the car had become flying. There is no way she wouldn't have heard the jet engines and felt the take-off. Also the noise in car's boot must have been loud, but she talked into the walkie-talkie and it came out fine.
Continuity mistake: During the car chase scene Bond overtakes a blue car partially off-road. We see Bond's car almost getting side-by-side by the blue car before we're getting an in-car shot of Bond's car being just behind the blue one.
Continuity mistake: When Bond goes into the belly dancer's dressing room, at first she does not have the golden bullet in her belly button, then she does.
Continuity mistake: During the belly dancer fight, Bond is pushed against a corner and the painting next to him remains unharmed. A shot later, from a different angle, it's skewed.
Continuity mistake: When Scaramanga blows the Bond dummy's fingers, the first shot blows the middle and ring fingers, and the second shot the pinky. When the angle changes, the index finger has also disappeared.
Continuity mistake: After Scaramanga kills Hai Fat, James meets Goodnight in a bar. As they drink the Phuyuck 74, Goodnight's fingers change position on her glass depending on it being a front or rear shot.
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]