When Gary Fenn leaves court and gets in the taxi, its rear number plate reads XYT 237. A few seconds later when the taxi stops, its front number plate reads ELK 318C.
When Gary and Marla are being chased by the bad guys in the black sedan, Gary manages to turn his car around and go in the opposite direction, yet additional long shots show they are going in their same original direction.
After learning that Tarquin (Alexis Kanner) is, in fact, an earl Gary Fenn (Roger Moore) addresses him as 'Your Grace.' That would be correct only if Tarquin were a Duke, which is very commonplace, either as a humouristic gag to the newly realized Earl, or ---- just a common mistake, and not really a goof (It just shows that Moore's character doe not care).
When executive Gary Fenn is questioning his staff about who planted a beautiful picture of an unknown model in his file, you can clearly see the shadow of the boom microphone on his chest.