Visible crew/equipment: When Tom Cruise comes back in off the street covered in ash, he slumps down by the refrigerator and very quickly the boom mic falls down into shot almost hitting Tom on the head.
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.
Continuity mistake: In the scene when the intersection is rotating, the camera is aimed up towards the church and starts to pan down. Tom Cruise runs into the scene and gets behind a car. The movement of the church shows the intersection is turning counter-clockwise but as it pans to the ground, the intersection is turning clockwise.
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.
Continuity mistake: Ray and Rachel are about to walk down into the basement at Harlan's house, the door on the right of the bulkhead is open and the door on the left is closed. In the view from the basement you will notice that the door on the left is open and the door on the right is closed.
Factual error: When Ray comes out from the basement to survey the damage, he sees a crashed plane. As he walks past the fuselage, there is a square window on the cockpit. Planes don't have square windows because to corners were proven stress points from the explosions of two De Havilland Comets in the early 1950's. After the investigations, all plane windows were deemed to be rounded to prevent another such incident.
Continuity mistake: When the tripod is taken down, the lights are flickered out on it. But in a couple of scenes later, the lights are working again on the tripod, right before the alien crawls out of the hatch.
Continuity mistake: This movie has to take place over at least 4 to 7 days for them to walk from New York to Boston. When they arrive in Boston, he has absolutely no facial hair growth.
Continuity mistake: When in their home basement, when the lightning starts they take shelter in the utility room and the door is a cross and bible style door that opens out. When Ray shuts the door against the fire he pushes it closed instead of pulling it, and it is a plain flat door. If there were two separate doors the fire wouldn't be burning through the still intact cross and bible door that Ray opens properly in daylight.
Continuity mistake: When they arrive at the ferry port a man throws something at the windshield which hits the top, and the screen around it shatters. In the following shot the car hits a pole and the damage has moved to the middle, and it's now a perfect hole.
Other mistake: When they arrive at the ferry port the crowd try to steal the car and it all turns violent, as if no one's seen a car for a while, but when they arrive on foot at the ferry there are several cars already on it, and no one bats an eyelid. The cars at some point must have driven through the crowd with no problems. Also the cars are taking up much needed space on the ferry.
Suggested correction: The cars could have been on the ferry before the crowd arrived. Or at least have been standing at the front when the ferry arrived. Besides, the fight over the car is for people not going onto the ferry obviously, but going somewhere else.
Visible crew/equipment: As Ray drives and Rachel screams, the camera crew and equipment are reflected in the window.
Audio problem: When the tripod walks over the hill at the ferry scene it walks over two trees. However, the first tree it stepped on doesn't make a cracking noise as it should. The second one does.
Audio problem: When Robbie helps the people onto the ferry, his speech is out-of-sync whilst he is talking. Most noticeable when he says "Hold on".
Continuity mistake: When the movie ends, Rachel runs to hug her mother and a strong wind blows large amounts of leaves a meter up. A frame later, from a different angle, the wind is milder and the leaves barely move.
Continuity mistake: Ray runs out of the house looking for Rachel and moves away some weeds blocking the door. When the angle changes the door is spotless.
Continuity mistake: When Rachel is watching the floating corpses in the river, the shots alternate back and forth between a wide angle where she is standing still and wind is not blowing, to a close-up where she is sobbing, moving her shoulders up and down rhythmically and her hair is moving rapidly.
Continuity mistake: When the movie ends and Ray meets his family, the street keeps swapping from sunny to shadowy back and forth.
