Continuity mistake: When the bad guys are outside the hotel in the convertible, they spot Lassard and one of them spits milkshake over the inside of the windshield. The milkshake disappears in the next shot.
Revealing mistake: When Lassard starts spilling golf balls from his golfing bag in the airport, look closely. Lassard is activating some sort of trigger/handle mounted on the bag to release the balls.
Visible crew/equipment: You can see the wire that pulls Proctor back before he catches the frisbee.
Continuity mistake: In the scene where Proctor goes water skiing, he is shown on the dock with no gloves and waves to the boat driver. Then when the boat takes off he has gloves on. When the water skiing ends the gloves are gone again.
Revealing mistake: When Hooks is carrying out her 'crowd-control' sequence, she causes the crowd to step back into a pool. However if you look closely, not all of them fall into the pool by accident, as a few turn round and deliberatly step forward into it.
Revealing mistake: Near the end of the film where Proctor kicks the chair towards Harris, if you look closely you can see the two grooves/rails that the chair slides along.
Continuity mistake: When the bad guys are stealing jewelery from the Museum Of Fine Art, they cut out part of the glass with a laser. The shot changes during cutting and the position of the jewelery inside the pyramid is different than in the previous shot.
Continuity mistake: When the 6 bad guys and Lassard are in the elevator and one passes gas and the rest move over, the bald guy (with blue tie) is against the wall. When the shot changes to an overhead view, he's now in front of someone who's against the wall. When the shot changes back, he's against the wall again, next to the guy he was just in front of.