While Peter and Robby are singing the hymn to Richard, they walk past the same white picket fence three times.
When the two girls come into Peter and Robby's dad's house, Peter gives Robby a sandwich and tells him to go eat it outside. Robby insists he needs his coat, and goes to get it. When he comes back into the room to go outside, he no longer has the sandwich.
The man performing t'ai chi in the park by the tree disappears.
When Richard is gluing the mirror onto the makeup container, you see him unscrew the cap and apply the "shoe goo". In the next angle, the cap for the goo has magically screwed itself back on.
When Christine is in the car for the first time with Michael we can see in the first shot that the seat belt is twisted twice on his chest. In the next shot, it isn't.
When the bag containing the fish falls off the back of the car, it doesn't appear on the road, even though there are enough frames in which it should have appeared.
Despite being set in Los Angeles, the bus showed in the last shot is a New York City MTA bus.