As Julie hurries through the room arranging flowers, one flower falls out of the vase, but she doesn't bother with it or even seem to notice it, continues arranging them, and then moves the vase to another table.
Early in the film, Preston storms up to Julie's bedroom and knocks hard on her door several times with his cane. The head of the cane seemingly leaves numerous dents in the wood. When Julie finally opens the door (inward into the bedroom), the dents have disappeared.
At the dressmaker's shop Julie holds up the red dress in front of her to see how it looks. It has sleeves. She takes it home with her and shows it to Preston. The next day is the ball and when she appears in it,the dress is now sleeveless.
Preston Dillard is seen entering a street level door, then going downstairs to the gentlemen's bar. New Orleans has a notoriously high water table, so buildings would not have had basements or lower levels.
The goof item below may give away important plot points.
Just after Preston Dillard collapses and Dr. Livingstone is asking for someone for help to carry him, between shots in the same scene we see Livingstone holding Preston by the hand, then not holding him, then back to holding him by the hand.