Factual error: The scene where Nightfox steals the Faberge Egg is all wrong. A laser security system must have a photoelectric receptor at the other side to detect if somebody pass between the two devices. As shown in the film, the laser beams points everywhere, so the system can't work and somebody could cross a beam without starting the alarm. Even if it was some weird system based on measuring distance it wouldn't work - if the laser hits the floor at an angle it won't bounce back to the source, it will reflect towards the ceiling.
Plot hole: How did Benedict have time to visit all of Ocean's 11 without them informing each other? (That is, only Danny should have been surprised to see Benedict.) He had to travel to Connecticut, Utah, Miami, London, New Jersey, Chicago, New York, Louisiana, Las Vegas, and Los Angeles. As soon as Danny knew, he was on the phone (presumably calling the others).
Visible crew/equipment: When Ocean tells the Nightfox about the fake Faberge, there's a shot of the Nord Train. When we see the left side of the train, watch its window and you will be able to see a camera and a cameraman reflected.
Deliberate mistake: Laser beams are normally not visible, except for a small dot where they hit a surface. Even if made visible, using smoke or dust or special glasses, they are thin as threads. Obviously something more visual was needed for Toulour's dance act, hence the thick beams of light.
Continuity mistake: Before some of the group is arrested, Brad Pitt is sitting at a restaurant table and 4 cops approach him (2 from the front and 2 from behind). In one shot, the two cops in the front are seen about to sit down, but in the next shot, they are just arriving and aren't even close to the chair. (01:18:50)
Visible crew/equipment: In the scene of Matsui's interrogation, you see Catherine Zeta-Jones leave the "pre-interrogation room", walk behind a glass through a corridor and finally enter the interrogation room; in the last seconds of her walk, you can see the shadow of the moving camera on the two-way mirror.
Continuity mistake: When Tess is told to put a pillow in her dress to make herself look pregnant, they hand her a square pillow. When she takes the pillow out later while a guest of the local jail, the pillow is round.
Plot hole: How does Agent Lahiri know that you needed to raise the pylons before it was possible to make the cross bow shot the boys needed to unlock the house in Amsterdam? Additionally, those pylons would not be accessible through water as they are planted in mud under the foundation of the building, not water.