Other mistake: In the scene where Geoffrey Rush is folding his dead friend's hands, you can see the dead man's fingers scratching to accommodate the final resting place of his hands.
Continuity mistake: When Harry visits the President to fit his new suit the President disappears behind a see-through folding screen to change. When he asks for the new pants and puts them on one can tell from the way he was standing behind the screen that he hasn't taken his old pants off.
Continuity mistake: When Andy and Harry meet at the open-air bar at the harbor there's a hut with a counter in the distant background behind which we see a waitress serving a customer. The camera cuts close to Harry for a moment, then to Andy, and we see the waitress walking by behind him, while the customer is gone. This happens way too fast.
Continuity mistake: After Pierce Brosnan enters the tailor shop, Russel explains how the secretary got wounded. She is in the back looking down, but when we hear her story a close up of her is shown turning her head to show us the scars. The shot changes to the previous wide angle and she is back in the original position, looking down, a split second later, without having had time to move her head.
Continuity mistake: When Andy comes to recruit Harry he first orders some suits, and he says that this order could develop into "the full monty" (hinting that the meaning of this phrase has turned into the opposite nowadays). At this point his right arm is stretched across the armrest, but when the camera angle changes his hand is up.
Factual error: When Pierce Brosnan sits in the plane and checks up info on his laptop, you can see that Savile Row is misspelled as 'Saville Row'.
Continuity mistake: When Harry sees his banker Ramon about his credit line Ramon suggests that he should sell the whole farm. At this moment the camera is on Ramon, and there is a reflection of the standing Harry in the window where we see that he turns away from Ramon. When the camera cuts back to Harry he turns around exactly in the same way we saw in the reflection.