Richie and friends are taken away from the house then Malcolm & Francis walk back into the house. Dewey is on Reese's right. When they walk across the room and the camera changes, Dewey is on Reese's left.
In the cold open the family are at dinner. When Dewey is viewed from the front he has a piece of bread in both hands. However, in the next shot he puts a drink down on the table and his left hand is on the table. Then when viewed from the front, he has a piece of bread held in both hands. Then when Malcolm speaks to camera Dewey's hands are on the table again. And After Hal throws the mashed potato at Lois, Dewey has the bread in his hands again.
Francis is home from military school. He opens a container of milk & smells it. Malcolm walks into the kitchen an Francis open a milk bottle AGAIN.
The boys are watching golf on TV. Sometimes Malcolm's arm is of the rear of the sofa. sometimes on the side arm of the sofa.
When the kids are dirtying up the living room, and Francis is blowing dust back out of the vacuum cleaner, the ceiling is missing, revealing the top of the set.