Revealing mistake: Bond drives his Austin Martin into a wall because he believes that the headlights appearing before him belong to another car (actually, they were the reflection of his own lights). When he first sees the lights, they are directly in front of him, but only just before the crash, the angle of the reflection changes. And the way the mirror was hung up when Oddjob looks at it, it was in no position to reflect the light the way Bond sees them.
Plot hole: The planes spraying the gas are flying too high and too fast for the gas to be able to have any effect on the soldiers on the ground as quickly as it does. While we later find out that the soldiers were faking the effects, the too-rapid response should have raised the bad guys' suspicions.
Other mistake: When several cars are pursuing Bond and Ms. Masterson through the woods, the first car falls prey to the smoke screen. As the second car continues pursuit, a man leans out of its passenger window to shoot at Bond. But he doesn't appear to be aiming, or even holding his gun tightly; the muzzle waves far to one side for the first several shots.
Plot hole: Jill was sprayed with liquid or atomized gold. Yet there is no overspray anywhere, no paint on the bed or sheets, no dripping from Jill's arm to the carpet. Even if the paint was quick-dry, there would have been some paint residue just from Oddjob moving her around to spray her whole body.