Here is a list of mistakes in the actual film; they are pretty minor. They are in fact so minor that I never noticed some of them until they were pointed out to me (and I have seen the movie hundreds of times!).

Also in the opening credits George Reeves's and Fred Crane's names as the Tarleton Twins are switched.

In the long shot of Twelve Oaks where buggies and horses are passing through the gate a white horse becomes transparent. Twelve Oaks has never been constructed and what we see is just a matte shot made by W.C. Menzies. He never had time to perfect it so there is no shade falling as the horse dissolves into the matte shot.

At the barbecue when Scarlett is looking for Ashley it seems that she moves to another room but when she spots Ashley he's descending the stairs in the main hall.

Scarlett wears a necklace at the barbacue: she doesn't have it on when she leaves Tara but she has it one when she enters Twelve Oaks. (unless she put it on in the buggy ;) )

When Scarlett talks to the Tarleton twins at the stairs at Twelve Oaks she refers to her dress as the 'old one that she wore just because she thought they liked it'. The opening scene was first shot with Scarlett wearing the green muslin barbecue dress and was later re-shot in the white-ruffled one. It was meant to be a reference to the dress she wore the day before, but luckily it fitted with the changed dialogue, so it's not really considered a slip.

At the barbecue, when Ashley and Melanie talk on the veranda, you can see a black 1930s car driving along the road in the distance!

At the Atlanta bazaar, just before Rhett Butler is introduced, Doctor Meade announces a happy news from the front. The crowd is cheering. When the drummer removes himself from the view we see Scarlett and Rhett walking away from the platform.

When Scarlett and Melanie are nursing the wounded soldier in the church hospital their shadows are not facing the same way as them.

When Scarlett leaves the hospital, a shadow of the boom mike is visible on the right hand side of the door.

When Scarlett runs looking for Doctor Meade she passes a lamp post with an electric bulb.

In the scene where the soldiers are laid out, two men carry a rolled up stretcher across the top of the frame, pass by Scarlett and then turn left. The man in the back steps on the leg of a soldier and leaves a footprint in the dummy's leg.

During the escape from Atlanta, when Scarlett leaves the house she's bareheaded and and later on in the buggy she wears a bonnet.

As Rhett and Scarlett flee Atlanta, he stops their wagon to comment on the fall of the old South. Interspersed with his comments are scenes of the wounded soldiers walking on the road. A bearded man smoking a pipe is shown carrying a fallen comrade. Several scenes later, this same man is shown now carrying a rifle. He then gives his rifle to another soldier and picks up the soldier he was seen carrying in the previous scene.

When Rhett kisses Scarlett goodbye on the road to Tara, he drops his hat on the ground but later on picks it up from atop of a fence post.

When Suellen and Carreen are picking cotton at Tara and Scarlett comes up to them audio and video are not synchronized. Scarlett says "Too bad about that" but her lips are not moving.

In the scene were Scarlett kills the Yankee intruder her hairnet changes size.

After Scarlett has killed the Yankee deserter Melanie takes her nightgown off for Scarlett to have something to wad the man's bleeding head with. Melanie's concerned about her being naked but she's obviously wearing a flesh-colored bra.

When the war is over, everyone at Tara runs to the front hall. Melanie runs down the stairs with empty arms but in the next shot she's holding her baby.

After Gerald's death, when Scarlett tries to think of a way to get money she mentions Rhett. Mammy asks "Who's that, a Yankee?" but her mouth doesn't move.

After Big Sam saves Scarlett in Shantytown he gets in the buggy with her but as they drive away Scarlett is alone and she's wearing a hat.

When Ashley is wounded after the rampage in Shantytown and he is carried into his room, Melanie picks up a lamp that has an electric cord attached.

When Scarlett leaves Melanie's house to run after Rhett, she leans on the post on the front porch and it wobbles back and forth.

Another interesting thing about GWTW (and I think it relates to movies from that period in general) is the fact that ages of the actors don't really match the ages of their characters. It's not a big deal with small differences but in some cases it's quite surprising. The story of GWTW spans 12 years.

Vivien was 26 and she portrayed a 16-year-old and a 28-year-old.

Melanie was one year older than Scarlett; Olivia was 3 years younger than Vivien (23 during the filming).

Clark's age suited Rhett's perfectly: he was 38 and his character was about that age at the beginning.

Leslie Howard portrayed a 20-year-old and a 32-year-old Ashley and he himself was 46 at that time.

Barbara O'Neil who played a 32-year-old Ellen, Scarlett's mother, was 27; only one year older than Vivien who played her daughter.

Ann Rutherford (Carreen O'Hara) was 19 and played a 13-year-old.

One other interesting fact: in this great American movie, three great American heroes are portrayed by British: Scarlett, Melanie and Ashley.