A Thief is a Thief (a.k.a. Magnificent Thief) - S1-E1
Continuity mistake: When the airline pilot enters first class to announce the baggage search, we see only 7 seated passengers and many empty seats. When the angle reverses, there are instantly 15 people seated, and almost no empty places. (00:25:30)
A Thief is a Thief (a.k.a. Magnificent Thief) - S1-E1
Continuity mistake: When Mundy and Claire are sitting in the car outside the apartment building, the rear view mirror has disappeared (probably removed to prevent it from obscuring the actors' faces). It mysteriously reappears later on. (00:42:45)
It Takes One to Know One - S1-E2
Continuity mistake: When Al leaves the casino floor to call Noah, he's smoking a cigarette. When he reaches into his jacket for the wallets he's just stolen, the cigarette disappears. (00:05:30)
It Takes One to Know One - S1-E2
Continuity mistake: While he hangs from the ceiling over the jewels, Al's trapeze is spinning slowly. But when the shot cuts to a close-up, you can tell from the stationary background that the trapeze is now perfectly still. In the next full shot, though, it's spinning again. (00:39:00)
When Good Friends Get Together - S1-E9
Continuity mistake: Mundy lines up six golf balls and hits one, leaving five - until the shot reverses angles, anyway. Then there are only three golf balls left on the ground. (00:40:00)