Continuity mistake: When Anastasia returns home with the contract in her hand, she enters her flat and the computer guy is just finishing fixing her laptop. During this scene her brown leather jacket disappears, but she is still holding the contract in her hand - this is a continuous scene with no time for her to remove the jacket.
Continuity mistake: When Ana has her first Red Room experience and Christian is unlocking the door, her hands are behind her body. As we see Christian insert and turn his key, her hands are in front of her and then behind when we see them both, and then finally in front of her again and they stay that way until they walk in. There was no time for her to change positions since you can see her in every shot.
Continuity mistake: When Christian and Ana have sex for the first time, there's one point where he takes her shirt off completely. Ana's shirt is short-sleeved with ruffle-like sleeves, but the shirt that Christian takes off looks long-sleeved, at least when he lifts it above her head.
Continuity mistake: At the end of the movie just before the belt incident scene, Ana walks over to the staircase and crosses her arms. The camera angle changes to face her and you can tell her arms are down by her side. This is evident by the fact that her sleeves don't appear to be "pressed down" or wrinkled but when we see her arms from the facing angle, they look the way they would with added weight. Added to that, if you look at Christian in the background, you can see him lift his head. Once the camera angle changes, you see him do the same motion again.