When Kate hugs Mark at the train station, her sunglasses fall off the top of her head, but in the next shot her glasses are neatly back up on her head.
When Dylan is taken to the hospital after the birthday incident, he has a black eye and a broken arm. When Kate asks his parents if they have seen Mark after he ran away, there is no trace of the black eye or the broken arm. Broken arms usually take a couple of months to heal in a cast.
As the kids are pulling the hose to trip Hank, right before he falls his hair and shirt are already wet from previous takes.
When Tom enters Charlie's bedroom to scold him for missing curfew the previous night, Charlie's bare feet are exposed outside the bedding. After a 4 second shot of Tom, the camera cuts back to Charlie, who is now completely covered, the bedding noticeably neater.
When Kate returns home, Lorraine and the younger sisters goes out to greet her. Lorraine tells Kate about Charlie, she is wearing a beige outer clothing with her left hand clutching it. When they enter the house in the next shot, she is wearing pink.
When Charlie drives the red family wagon up to the house you see an Illinois license plate. On the plate all the numbers are together. Illinois plate numbers are separated.
When the family moves to Chicago an aerial shot shows their cars on Lakeshore Drive, followed by the two moving vans. Trucks are not allowed on Lakeshore Drive, not even pickup trucks. If they are moving from Midland City to Evanston, which is just north of Chicago, they would have taken I-55 to I-290, which is 14 miles west of Lakeshore Drive.
The train is seen to be a double-decker commuter train, but the car in which Mark is found is a single-decker.
When Tom and Mark depart from the Amtrak station, the next aerial shot of the train shows a Metra train, not an Amtrak train.
After the kids vote to move, Tom is lying on the bed reading them out to Kate. There are 14 votes and only 11 of the kids voted. However, it is likely that Nora, Tom and Kate also voted.
One may question how Mark was able to board the Amtrak train without meeting the age requirement to have purchased a ticket. It is a common practice of Amtrak conductors to make their rounds taking tickets several minutes after the train has left the station, so he could have boarded and found a seat with no question.
When Dylan gets up after the chandelier crash, his parents begin to take off his helmet and safety pads; however, he is clearly rolled out the door still on skates and has an elbow pad on his right arm. In the next shot, we see the Shenks walking down the street, and neither the skates nor the pad are anywhere to be seen.
CORRECTION: They could have stopped after exiting the house to put his shoes on and take the skates/remaining pad off. There is some time between when they roll him out and when they are walking across the street.
CORRECTION: They could have stopped after exiting the house to put his shoes on and take the skates/remaining pad off. There is some time between when they roll him out and when they are walking across the street.
In the moving scene, the van has the parents, the dog, and 10 kids in it. The actual model of the van looks like it doesn't seat that many people.
When Tom is looking in the phone book for a babysitter, one of the close shots is flipped (reversed).
When Kate opens the closet doors, she flinches before the toys fall on her.
Toward the end of the movie, during the holiday dinner, one of the scenes is clearly playing backwards. It features Jessica (red-headed girl), Kim (blonde girl) and Mark (red-headed boy with glasses).
(at around 1h 04 mins) The gas bottle next to the bouncy castle in knocked over. At the base can be seen a very odd piece of grass which is obviously only there to hide part of the rigging for the stunt - a hinge mechanism.
When Tom and Dylan are hanging from the chandelier, there is a shot of the top of the chandelier breaking from the ceiling, then there is a cut to Tom. If you watch this in slow-motion, a crewman holding a boom microphone is visible on the floor below.
Two times, when Tom Baker looks up at the Illinois Poly University scoreboard, there's a palm tree behind it.
For some reason Sarah and Henry are never shown going to school when the family moves to Chicago, even though there are scenes with the twins, Jake, Mark, and Mike going to the elementary school/junior high, and Charlie and Lorraine going to high school.
In the original movie release, the boom mic is shown at least six times during the whole film. When it reached TV and video the errors were gone.
The dad requests a babysitter for twelve children, although four of his kids are much too old to need a babysitter.
When Mark gets bullied at school and his glasses are knocked off, he struggles to see them and pats around to find them. Later, he is in bed and looks at a photo of him and his mum, without wearing any glasses. If he is able to see this photo, then he should be able to find his glasses easily.
Kate's publishing friend is named Diane. But she is credited as "Diana Philips".
In Mark's room at the new house. Mark's room has a slide that leads to the bushes outside. Yet when the kids get grounded and they can't go to their neighbor's birthday party. But Sarah tells them all that she's going and asks who's with her. They are seen sneaking out by roping down out of the window. They could've used the slide in Mark's room.
When Dylan is being wheeled out of the hospital, Tina accidentally runs into the wall as the gurney passes through a doorway.