When Chester See's character is buttoning his shirt in the beginning of the movie he finishes all of his buttons and the next cut he is still working on those darn buttons again.
The Michigan license plate on Eli's truck is on both front and rear bumpers. In reality, Michigan plates are only on rear bumpers. Though you can put anything you wish on the front bumper of your vehicle in the state of Michigan. In Illinois however, you are required to have a license plate in both the front and rear of your vehicle. (Source: Michigan Resident & Michigan Secretary of State website)
When Elise has just arrived at camp and she's sitting by the lake, writing, a person is seen just barely walking into the frame, but in the next frame, she's still sitting alone.
When Elise is in her apartment drinking and calling Sally multiple times, the boom is seen moving back and forth in the mirror on the shelf on the back wall.