Revealing mistake: When CG and IB are on the plane, watch the scenery in the window. It appears to be going in reverse.
Plot hole: During the wine cellar scene, Devlin & Huberman are kissing & Sebastian catches them & confronts them. Sebastian then tells Huberman to go to her guests. There is no way that Devlin, who loves Huberman, would not automatically go to Prescott & tell him to immediately pull Huberman from the Sebastian house. Her cover is compromised & her life is in danger! Sebastian saw them both near the wine cellar & will now go to the wine cellar to get the wine (that's why he was down there). He will see that the key is missing. Sebastian is not stupid; he will do the math. If nothing else, Devlin should tell Huberman to not, under any circumstance, put the key back on Sebastian's keyring, since this will prove Huberman's guilt to Sebastian. But neither Prescott nor Devlin say a thing to Huberman (which is understandable in Prescott's case - he doesn't love her - but not Devlin). Devlin is a spy. He should have, & would have, known better.
Continuity mistake: When Grant and Bergman are sitting at the sidewalk café, the rear-screen shots show the same woman two or three times coming up the sidewalk and turning to our right. Watch for her in the background over Grant's shoulder.