Continuity mistake: We see a close up of Gabriella slipping in some milk, but in the wide shots there is no milk or carton on the floor. (00:41:30)
Continuity mistake: When the red Ford Bronco is driven off the ferry (ignoring all the impossible factors required for it to successfully do so), it flips through the air and contacts the water going backwards, its right/rear tail light entering the water first. The closer next shot shows the truck sink somewhat as it continues to flip backward, onto its roof. The very next shot shows the interior of the truck as it enters the water right-side up and going forward as water rushes in. Denzel lurches forward and down, driving his face into the water that is about waist level. The next exterior shot is underwater as the truck now lands in the water, nose first and right-side up. It then begins the expected slow dive, nose-first. (01:52:30)
Continuity mistake: After Eisenheim has disappeared, literally, from stage, Uhl and the policemen search his office. There, Uhl finds Eisenheim's notebook with the design of the locket in it. There is a large tear in the middle of the paper. It disappears when the inspector looks at it again after he has found the locket in the Prince's barn. (01:31:00 - 01:31:45)
Factual error: At one point, a screencast of a computer screen shows a video of Barry Brickman on the desktop environment of Windows XP (operating system, developed by Microsoft, released in 2001). However, the app that plays the video is QuickTime for Mac (which runs on Mac OS only), not QuickTime for Windows (which runs on Windows XP). These two versions of QuickTime are almost identical in every respect, except for their title bar (the narrow horizontal area above the video). (00:19:15)
Continuity mistake: Carl and Dupree are having a little party while Molly is at work. When Molly walks in Carl grabs a glass of liquor, and as it cuts back and forth to him it changes from a bottle, to a glass, to a bottle and back to the glass.
Continuity mistake: During the last few scenes in the movie, when Hannah asks Jenny if she needs help with the plane, they knock knuckles together. When the shot is taken from behind Hannah, she is shown wearing gloves, but when the shot position changes to behind Jenny, the gloves magically disappear.
Continuity mistake: In the scene where Matthew McConaughey makes dinner to confront his parents and Sarah Jessica Parker about scheming to get him to move out his wine glass is magical. Before revealing he knows what is going on McConaughey stands up and drinks all of the wine in his glass and sets it back on the table. Seconds later, the wine glass has been magically refilled. And during his speech his wine glass jumps magically into his left hand before mysteriously returning to the table.
Continuity mistake: When Syvia ignominiously trips at the beginning the flamenco lesson, she stays on the floor with her hand on her thigh in the close-ups, on the floor in the intermediate wider angle. (00:17:45)
Continuity mistake: When Roger is drunk and getting into bed, his alarm clock changes from 11:39 back to 11:38.