Continuity mistake: There is no knife on the table when the wife enters the kitchen at the very end, however, she walks straight to Louis, hugs him and then magically a knife appears at the edge of the table which she picks up and uses to stab him (implied - the movie actually ends at that point).
Continuity mistake: When Ellie falls from the tree after the rope from the tyre breaks, Louis runs with his wife to see how she is. Louis is wearing a white T-shirt with the sleeves rolled up. When Rachael yells "Gage!", now you see Louis wearing a white striped unbuttoned shirt and sunglasses. But when Louis is running for Gage, he's back to his white plain T-shirt with the sleeves rolled up.
Continuity mistake: In the scene where Louis goes to dig up Gage's body, the grave is covered with dozens of white flowers. A police car drives up with the lights on and Louis turns to look; after Pascow warns Louis not to cross the barrier because the earth is sour, then the camera cuts back to Louis, and the flowers are gone.
Continuity mistake: After Gage has been killed and Judd comes in the kitchen to comfort Louis, Louis is sitting at the kitchen table and Judd goes to sit down on a chair that is tucked up to the table. In the immediate next shot Judd sits down without pulling the chair away from the table.
Continuity mistake: In the scene where the father is in Jud Crandall's house looking for Gage, he is upstairs in the bedroom kneeling beside the bed holding a syringe. After he sees Jud dead, he gasps and you see him bite his fist with his right hand (the hand which was previously holding the syringe). Then the camera cuts back and he is again holding the syringe in his hand.
Continuity mistake: When Ellie falls off the tire swing at the beginning of the film, the tire shown in the first shot of her on the ground is not the same one that was tied to the tree. It is a whitewall tire with brand new tread, and the rope is nowhere to be seen in this shot. A moment later when her parents run over, the older worn-down tire with the rope tied around it reappears.