At the beginning, Lucy is in the nursery with Little Ricky and puts him to bed in his crib, laying on his stomach. The one crib bumper pad is on the side next to where Lucy is standing. Ricky then comes in and Lucy motions him over to the crib. He waves to the baby and in the following closeup of the baby, the bumper pad is now on the other side of the crib.
Lucy repeatedly runs from the Ricardos' living room, through the Mertzes' living room, and through a door stage right, which presumably leads to their kitchen, out their back door, across the balcony and back to her kitchen. But in The Sublease (1954), characters make frequent trips to the Mertzes' kitchen, which is now stage left. Because Fred is such a cheapskate, it isn't likely that he would have done such a drastic remodel.