Continuity mistake: The interior layout of the Burnham's house does not match the exterior of the house. This is illustrated in the scene in which Jane comes inside after Ricky is taping her for the first time. She walks in the front door and goes directly into the dining room to peer out of one of the two side windows. If the interior of the house matched the exterior, she would not have been able to peer through those windows because they would not have existed. Instead, the garage would be there. (While there may be a window on that side of the dining room that does face out near the garage - extended external views of the house from that side are not plentiful in the film - there are still not two windows which face out in that direction. The garage would block one.) (00:20:07)
Continuity mistake: When Caroline is cleaning the house she is trying to sell, she's in the kitchen cleaning the counter tops. The layout is her cleaning the breakfast bar counter and the sink is behind her to the left of her. When she takes a buyer through, the kitchen layout is exactly the opposite. If you look at the breakfast bar counter top, the sink is now on the right side. Also, you'll notice the "wall" to the left of the counter top now is pushed back a little - almost like they didn't align it correctly when they put it in for shooting.Ben's Mom
Continuity mistake: During the night out at the estate agent's party, and back at the house that same night when drinking root beer in the kitchen, Kevin Spacey is wearing a t-shirt under his shirt. After hearing his daughter and friend talking about him working out he goes to the garage, finds his weights and takes his shirt off, but there is now nothing underneath. (00:28:45 - 00:38:50)
Continuity mistake: In the scene where Lester is telling Carolyn and Janie that he quit his job if you watch Carolyn's drink you see that it changes drastically from shot to shot, between having lots of ice, not that much ice, being quite full, not as full, etc. And she never even takes a sip. (01:05:07)
Continuity mistake: In the scene where Col Fitts comes into Ricky's room to retrieve the urine sample the refrigerator is on the left of the door as is the bed. This is also how the room is set up when Jane is being filmed by Ricky in Ricky's room. However when Lester is in Ricky's room to buy marijuana from him for the first time the bed is on the opposite side of the room. The bed is also like this when Col Fitts is hiding in Ricky's room after Ricky delivers more marijuana to Lester later in the movie. (00:47:46)
Continuity mistake: Lester decides to exercise his body after listening a conversation between his daughter and her friend Angela. He goes to the garage and looks for his instruments, dropping several things to the floor. We can see some of them, but a second later when he didn't even tried to pick them up, a big one has suddenly dissappeared and never comes back.