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.
Revealing mistake: After Bond and Felix first meet, the background behind Goldfinger is a blatant rear projection. Notice how the couple behind him is completely frozen, as if someone forgot to start the projection running. (00:10:00)
Revealing mistake: When Felix points at Goldfinger's card-game partner, watch the two extras on the right. They stand perfectly still for several seconds before suddenly starting to walk—waiting for the crew's cue. (00:10:04)
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.