When Johnny's parents come to visit and he rides off on his horse in a huff, he initially gets on a brown horse, but when he jumps the hedge in the next shot, his horse is white.
In the episode, Alice is looking for a preschool for her daughter Penny. They look at a particularly fancy preschool where Prince Charles' kids are rejected. When this episode aired, his children would have been 10 and 12, way too old for preschool.