Continuity mistake: After Rachel tells Ray that Robbie took the car, when Ray runs down the steps long shadows are cast. When Ray turns around to see what everyone is looking at, all shadows are gone, only to reappear in the next shot. Then when Ray runs to his yard, the angle of his shadow is entirely different. (00:13:30)Super Grover
Continuity mistake: As the hole begins to crack in the overhead wideshot the crowd moves back, and the florist is at the top center of the screen with hardly anyone near it. Yet, in the next close-up, suddenly there are dozens of people standing in its path, as the crack dramatically approaches the florist. (00:21:15)Super Grover
Continuity mistake: When the asphalt quakes in front of the church in the overhead shot, just as the huge gush of water shoots up from the ground, in the foreground a person is leaning way out their window aghast at the goings on. In the next shot that person is gone and the window is shut. (00:22:45)Super Grover
Continuity mistake: Whilst Robbie is helping the people onto the ferry in the overhead shot, Ray holds Rachel beside a red car down below as they are both avidly watching Robbie's heroism. However, in the next close-up Ray is just now approaching the car, amongst a greater crowd of people. (01:02:20)Super Grover
Other mistake: Mary Ann and Tim's basement, and Ogilvy's cellar are the same set, just dressed differently; note the positioning of the windows, the stairs, even the little room off to the side. Also, some items in both the basement and cellar are the same, for instance the chair. While they are in the basement and the plane is crashing, before they run into the side room, Ray grabs his gun off of that chair and later in the movie when they are in Ogilvy's basement, Rachel is in that chair when the aliens are in the cellar.
Audio problem: When Ray carries Rachel out of Mary Ann's destroyed house, Ray and Robbie walk past some wreckage and are near the van, yet in the next shot they just start walking past that wreckage again. Additionally, the audio is not in sync with Ray's lips in the first shot. (00:45:40)Super Grover
Continuity mistake: In Boston, when Mary Ann lifts Rachel, she holds her daughter then turns to face Ray and says, "Thank you." Behind them, up the stairs, the left front door is already wide open, yet in the next shot both doors are closed until her parents dramatically open them. (01:47:30)Super Grover
Continuity mistake: When Ray and the kids are driving down the freeway, there are several cars stopped randomly so they have to swerve a lot. But when it shows them inside the car, talking, they are driving perfectly straight. When it shows them from the outside again, the random cars are back and they start swerving again.