As Lucy helps take off Little Ricky's jacket, the front door of the apartment is completely open. In the next shot, Fred enters the apartment by opening the door.
Little Ricky is in kindergarten in this episode. However, only last season he was celebrating his third birthday in "Lucy is Homesick in Italy."
When Ricky comes back from attending the fathers' meeting at school, he tells Lucy, Ethel, and Fred what their parts are going to be in the pageant. He tells Ethel that she is going to be the fairy princess because the costume will fit her. Lucy agrees and pantomimes the size of the woman who wore it last year and says it will fit Ethel perfectly. There is no way Ricky would know at the meeting that the costume would fit Ethel.