When Lois punches Peter, they are standing in front of the stereo and Peter is punched away from the stereo but then collides with the stereo from the sofa and walks to the sofa and Lois is there too.
When Chris and Meg are raking leaves, there is one yellow leaf and one brown leaf on the lawn between them. When Meg picks both of them up to smash them together, they are both brown.
When Peter and Lois roll/run down the stairs during the fight, their framed wedding picture on the stairway wall comes and goes.
As Peter is running off the dock towards the car, you can see half of his body disappear.