Continuity mistake: Before Han is frozen in carbonite, you can see there is nothing by Leia. When the platform Han is standing on begins to drop, we return to Leia and she now has an Imperial stormtrooper standing by her.
Continuity mistake: When Han says "Watch this!" when trying to get the Millennium Falcon to jump into hyperspace, C3PO turns his head around twice.
Continuity mistake: In the original 1980 release of The Empire Strikes Back, the group accompanied by Billy Dee Williams just walked from the deck with the Falcon inside the halls of the city. There is a man fixing a wall and next to that man is a window, the window shows a blue sky with a couple of buildings that were obviously drawn in the scenery. However in the last scene where Harrison Ford was hugging Billy Dee Williams the sky was orange. This shot only last for a second as the round small window is drawn wrong. But all of cloud city is a painting so its no surprise.
Continuity mistake: When the Millennium Falcon goes towards the bottom of Cloud City towards the end of the movie, we cut to the inside of the cockpit and Lando says "Look, someone's up there" when he notices Luke on the weather vane. At this point you can see Lando's right hand is on Chewbacca's seat when he says this, but when the camera is behind Lando in the next shot, his right hand is no longer on the seat.
Continuity mistake: At the rebel base, Leia is informed that there is nothing more can do about Han and Luke until the morning and agrees to the hangar doors being closed. In the wide shot, you can see the doors starting to close, although the code hasn't been put in yet. In the next shot the code is put in and the doors start closing again.
Continuity mistake: When Han, Leia and Chewbacca are captured by the Imperials in Cloud City, Lando says, "I'm sorry", to which Han replies, "I'm sorry too." At this point, Chewbacca is looking at Lando, but as the shot changes he is looking at Han, and then looks at Lando a second time..