In the scene where Cristine is first attacked by the Lamia, she gets a visible cut on her lip. In the following scene, where Cristine makes out Clay, the cut is gone. In the next scene, however, the cut returns.
When Christine is at Clay's parents house eating the cake, she first eats and touches it with a fork. Once the vision stops she starts eating again, only this time with a spoon. Later when the fly pops out of Christine's mouth, Clay's mom looks at an uneaten piece of cake (maybe Christine's, maybe not) and it has a fork.
During the séance there is a thundering noise that gets so loud that the participants cover their ears. When it stops, the faces of the participants are shown. A closeup of Christine shows her without her hands over her ears. After the closeups of the others with their hands over their ears, the group as a whole is shown and Christine is taking her hands away from her ears.
During the séance, just before the ancillary spirits appear, there is an overhead shot of the table. The white goat is not present in that shot although it was chained to the table at the start of the séance.
Throughout the film Christine wears a ring on her finger which originally is on her ring finger on her right hand and then changes to her middle finger on her left hand. In the final scene, during the closeup of her hand, we can that the ring disappearing and appearing multiple times between frames.
When Christine tries to get out of the grave that is filling with water, she grabs onto some rocks at the corner of the grave. The rocks immediately pull away and fall into the water. Unfortunately, the rocks can be seen "floating" on the water (fake foam studio rocks).