Character mistake: When Melanie and Scarlett are talking with an (off-screen) wounded Confederate soldier, the soldier says he hasn't heard from his brother since Bull Run. Only Northerners refer to that battle as Bull Run; Southerners have always referred to it as Manassas.
Continuity mistake: When Dr. Meade announces General Lee's victory (and later Rhett Butler as a special guest) at the "Monster Bazaar", he speaks to a backdrop showing the audience with a soldier with a drum standing left to him. Behind him, a couple in black is dancing. When he moves, Rhett and Scarlett are revealed, going to the rear of the dance floor. Clearly they haven't met at that point, as they are introduced by Melanie moments later.
Factual error: Scarlett is seen walking on the main street on the way to the hospital. You can clearly see a light bulb in one of the street lights. (01:05:25)
Revealing mistake: In the scene where Ashley is brought back wounded from the raid where Scarlett's husband Mr Kennedy was killed, Melanie grabs an oil lamp to follow the man carrying Ashley to the bedroom and you can see an electrical cord hanging down from it. (00:50:45)
Continuity mistake: In the scene where Scarlett is talking to Ashley about owing the carpet bagger 300 dollars right before Ashley kisses her you can see a definite change. Ashley has different dirt on his face and Scarlett's dress looks lighter. Her hair is also loose in different places.
Other mistake: The credits for the Tarleton brothers in the opening credits have the twins switched with their actors. George Reeves doesn't play Brent, he plays Stuart. You know this because in the opening scene the two boys are talking about the party and asking Scarlett for dances, and George Reeves points at his brother and calls him "Brent."
Continuity mistake: The shadow scene in which Scarlett and Melanie care for the wounded in the Atlanta hospital was filmed with two doubles. Since Leigh and de Havilland were standing at the wrong angle to cast the shadows, two stand-ins were positioned in front of the high-intensity light. The shadows of the doubles were reflected on the wall behind the stars, and the result was a stunning visual effect. Yet upon a closer look, the gestures of the stand-ins are not totally synchronised with the movements of the stars. (00:56:30)
Continuity mistake: In the scene showing guests arriving at the Wilkes' barbecue, you see buggies and carriages driving through the front gates and up the drive toward the Wilkes' home. The carriages clearly create shadows on the ground, but not on the stone pillars of the gates. This is because when the movie was filmed, there were no actual gates. The gates were later "painted" into the frame. Proving someone forgot to "paint" shadows onto the pillars. (00:17:15)
Continuity mistake: When Scarlett is attacked in the woods on a bridge while on her way to the lumber mill the buggy very nearly goes off of the bridge backwards. Then Scarlett faints, but when the camera returns to the full shot of the buggy, suddenly it is squarely in the middle of the bridge and in no danger at all of falling over the edge.
Continuity mistake: While our protagonists flee from the burning Atlanta the carriage stops. A bearded soldier walks by carrying another man. A few moments later the camera focuses on a young man who collapses and is being picked up by exactly the same guy who was carrying him already. The mistake wouldn't be as pronounced if it weren't been one of the few instances where action by extras is highlighted. (01:23:25)
Continuity mistake: When Aunt Pittipat serves her last Madeira Uncle Peter is standing on her left. Then the camera angle changes to a close-up on her, and in the next wide shot Uncle Peter is standing on her right. (00:52:00)
Continuity mistake: When Scarlett undresses for her nap after the 12 Oaks barbecue, she unties a small bustle from around her waist. She didn't have this bustle on when Mammy helped her dress for the barbecue earlier that morning.
Suggested correction: Was it under the main bustle?
Scarlett is laced up then Mammy helps her on with her dress. Looks like Scarlett is just wearing her corset (stays) with pantalets. Selznick probably adhered to the customary undergarments in the nap scene but chose no film time for the hurried scene where Gerald counts to 10 to make Scarlett hurry down to his carriage.
Audio problem: After Scarlett leaves the hospital in disgust she runs into Rhett. When she climbs into his buggy she asks him if he can take her to her Aunt's, but her lips aren't moving. (01:04:15)
Continuity mistake: When Scarlett fights with the two men on the bridge she loses her hat. When she drives off her head is still bare, but but seen from behind in the next shot the hat is back. When Big Sam catches up with her the hat is gone again. (00:41:45)
Continuity mistake: In the scene when Rhett is saying goodbye to Scarlett before he leaves her on the road to Tara alone, he throws his hat behind him onto the road and takes Scarlett into his arms. However, a few moments later, he picks the hat up from the fence at his side along with his coat. (01:26:55)
Continuity mistake: When Scarlett and her father talk in the setting sun his riding whip casts a shadow on her face although the sun is in their back. (00:11:30)
Revealing mistake: When the carriages arrive at Twelve Oaks they turn transparent halfway down the driveway. (00:17:15)
Continuity mistake: When Rhett stops the carriage on the bridge at the turn for Tara, he pulls the brake to keep the carriage from moving. When Scarlett drives off in the carriage, she does not release the brake. (01:27:50)
Visible crew/equipment: When the O'Hara family does their prayer, you see two boom mic shadows on the ceiling. (00:14:15)
Revealing mistake: When Scarlett finds Twelve Oaks completely destroyed, the carriage in the background is not real. As Scarlett walks toward the staircase, both the carriage and Prissy are not real, it is just a picture that has been painted to make it look like they are sitting there.