Revealing mistake: During the glider scenes, they use aerial shots of stuntmen in a real glider and then a prop/dummy one with a blue screen for the close up shots of Thomas and Catherine inside the cockpit. The actual glider has a second rear cockpit control box that you can see in all the aerial shots.The rear pilot is at least 5 feet back from the front one. In the close-ups, with the prop/dummy one, the rear cockpit box is gone and they show Thomas actually leaning on Catherine's back. The actual glider also has a much larger wingspan, fuselage, and cockpit. Again, you see this during the take off shots and all the aerials. When they land in the field and crawl out of the dummy/prop, the tail is only about 5 feet back from the cockpit. (01:04:50 - 01:06:05)
Continuity mistake: The Jeep and Cobra Mustang are shown covered in mud as they climb the hill to the house in Martinique, however when they arrive at the top, they are clean again.
Continuity mistake: When they land in Martinique, and are on the airstrip loading up the vehicles, their luggage and the painting go into the second vehicle, a shiny black jeep. However, when they show the aerial shot of them climbing the mountain to Crown's house, the jeep is now painted in camouflage colors. (01:08:10 - 01:08:55)
Continuity mistake: Thomas Crown comes into the police station to identify the thieves. As he is getting ready to leave, Catherine eavesdrops on his conversation as she fixes herself a cup of coffee. She then watches him out the window, drinking her coffee, as he runs to his car. The paper coffee cup changes from a purple swirl design with a little bit of green to a blue and white, geometric border with what appears to be an Asian design. (00:32:30)
Continuity mistake: When Crown returns home straight after stealing the Monet, the high external shot shows him open the door with his left hand. In the next internal shot he is opening it with his right hand. (00:21:25)
Revealing mistake: When Crown enters his office for the first time, he goes up to the window and looks at the river. Just as the camera points out the window, a bright light is seen to shine on Crown's face so that his reflection in the window is clear. (00:06:25)
Visible crew/equipment: When Thomas Crown exits the museum after having stolen the Monet, we see a couple of strange characters, probably crew members, standing on the ledge of the building just behind the cab he gets into. The man with the mask is the most interesting. (00:20:15)
Continuity mistake: In the scene at the of the movie where Catherine is whispering in the ear of Thomas, you can see that the ear is not from Thomas. Compare the ear with earlier scenes and its clear this must must be someone else.
Other mistake: When Catherine breaks into TC's house and is searching for the Monet there is a scene where she admires The Mirror Of Venus, the footage of this scene has been flipped because the painting is a mirror image of it's actual composition.
Revealing mistake: During all shots of the actual glider, you can tell very obviously it is two stunt men in very bad, fake looking wigs. The one up front, "Catherine" now makes her look like a football player. He also has on a long red wig that goes to his shoulders, which is longer than Catherine's hair. In one aerial shot, the stuntman sitting in the rear, which is supposed to be "Thomas", has this dark black bowl cut wig that is parted down the middle and slicked to his head. (01:06:05)
Continuity mistake: In the first scene in the gallery when TC is admiring the Haystacks painting, he is preparing to eat a croissant. In the shot looking at him face on, he maneuvers the croissant into position in the bag it is in, so that he can begin to eat it. However, in the next shot - a longer distance profile shot - just after he answers Bobby's question, he is already chewing on a mouthful and starting to tear another piece off. (00:04:00)
Factual error: When Russo and Brosnan are talking at the meal when they first met it is said that he "went from Glasgow to Oxford on a boxing scholarship". Oxford have a firm policy throughout the colleges of only offering academic and music scholarships.
Other mistake: Near the start of the movie when Thomas Crown enters his office for the first time, he uses a magnetic swipe card to access the elevator to his office. After he swipes the card, you can hear a 'ding' and the sound of elevator doors opening but you'll notice as he first inserts the card into the reader that the doors are already open. (00:05:30)
Plot hole: The "titanium-reinforced" briefcase Thomas leaves to block the descending security gate would have had his fingerprints all over it.
Factual error: The Trojan horse is transported into the vault area by a motorised pallet jack. The pallet jack operator is behind the load and his forward vision is totally obstructed by the load. The operator should have been in the front (as required by OSHA). Also they must turn the load around in the narrow hall because later the operator is in the front.
Continuity mistake: The theft occurs on one of the hottest days of the year, as pointed out by the guards. When Katherine arrives that night, she is wearing a coat. The investigation lasts a week or two, and throughout that time, they wear jackets and even top coats. Katherine's breath is frosty in the air a week or so after the theft. The weather apparently went from really hot to really cold in a week or so - NY weather may fluctuate a bit, but not to that extent.
Revealing mistake: In the opening scene, the outdoor setting is supposedly an unusually hot autumn day. However, outdoor shots show several people with jackets, long coats, and almost no short-sleeve tops or shorts.
Plot hole: How did Catherine manage to show up at the original crime scene at the same time that the detective arrived? He came from across town; she came from Europe, as proved by her "jet-lagged" comment the next morning.
Plot hole: The beach could be reached only by vehicle, but they only had one car and they arrived separately.
Continuity mistake: When he first sits in the museum, his watch shows about 4:30. Next scene, as the truck pulls into the museum, the clock on the right wall shows either 1:30 or 6:05. Next scene as he walks into the office and says good morning, it's shortly before 12 noon. (00:02:29 - 00:04:00)
Answer: On the commentary track for the DVD the director states that he has no idea how Thomas Crown stole the final painting.