Visible crew/equipment: Oliver (a dog) jumps up on Uncle Bill's bed and starts barking at him. The real reason the dog is barking: in the shots of Oliver, the shadow of a towel or some sort of toy can be seen being waved around in order to agitate the animal. It even briefly pops into the shot a couple of times.
Other mistake: Season 5 sees the family celebrating and reminiscing when the children came to live with Uncle Bill. Buffy and Jody were 6 when they came to live with Uncle Bill. This would make the twins now 11. In a later season 5 episode, Jody is trying to get a female classmate to like him in order to secure a stamp he wants for his collection, the Spanish triangle. His antics catch the concerned eye of his Uncle Bill who asks a few times during the episode, "is it normal for a 9 year old boy to be interested in girls?"