When Jesse is near the front door and begins pouring gasoline in the living room, a shadow of a different person can be seen going across the fireplace.
At around 9:15, baby Holly is being carried by Skyler as she enters the White residence. The baby is wearing shoes in the first shot, but only socks in the shot right after.
When talking to her therapist about untraceable poisons, Marie mispronounces saxitoxin as "saxitotoxin".