When Tara and Christian are by the pool, Tara's sunglasses are on her face whenever the camera faces her. But her sunglasses are on her head when the camera is behind her.
When Tara and Christian are by the pool, in some scenes we can see direct sunlight shining on Christian's face and Tara's hair and back, but when the scene changes to another angle there's no direct sunlight at all.
On the minute 52:00 Tara is saying that she will take a shower and going out. During this scene, outside is bright and shine and very sunny. But when she is leaving home, outside is almost middle of the night.
When Ryan comes upon Cynthia stabbed to death in her apartment, the camera does a slow close-up pan across her "corpse" in which the actress's pulse is clearly visible in her neck.
In the first scene Ryan asks how long Christian and Tara have been seeing each other, the answer given by Gina is a year but when Ryan comes clean to Gina later in the movie he says he and Tara broke up three years ago when she started seeing Cristian.